/** * This module implements the workhorse functionality for string and I/O formatting. * It's comparable to C99's vsprintf(). * * Macros: * WIKI = StdFormat */ /* * Copyright (C) 2004-2005 by Digital Mars, www.digitalmars.com * Written by Walter Bright * * This software is provided 'as-is', without any express or implied * warranty. In no event will the authors be held liable for any damages * arising from the use of this software. * * Permission is granted to anyone to use this software for any purpose, * including commercial applications, and to alter it and redistribute it * freely, subject to the following restrictions: * * o The origin of this software must not be misrepresented; you must not * claim that you wrote the original software. If you use this software * in a product, an acknowledgment in the product documentation would be * appreciated but is not required. * o Altered source versions must be plainly marked as such, and must not * be misrepresented as being the original software. * o This notice may not be removed or altered from any source * distribution. */ module std.format; //debug=format; // uncomment to turn on debugging printf's import std.stdarg; // caller will need va_list private import std.utf; private import std.c.stdlib; private import std.string; alias bool bit; version (Windows) { version (DigitalMars) { version = DigitalMarsC; } } version (DigitalMarsC) { // This is DMC's internal floating point formatting function extern (C) char* function(int c, int flags, int precision, real* pdval, char* buf, int* psl, int width) __pfloatfmt; } else { // Use C99 snprintf extern (C) int snprintf(char* s, size_t n, char* format, ...); } /********************************************************************** * Signals a mismatch between a format and its corresponding argument. */ class FormatError : Error { private: this() { super("std.format"); } this(char[] msg) { super("std.format " ~ msg); } } enum Mangle : char { Tvoid = 'v', Tbit = 'b', Tbool = 'x', Tbyte = 'g', Tubyte = 'h', Tshort = 's', Tushort = 't', Tint = 'i', Tuint = 'k', Tlong = 'l', Tulong = 'm', Tfloat = 'f', Tdouble = 'd', Treal = 'e', Tifloat = 'o', Tidouble = 'p', Tireal = 'j', Tcfloat = 'q', Tcdouble = 'r', Tcreal = 'c', Tchar = 'a', Twchar = 'u', Tdchar = 'w', Tarray = 'A', Tsarray = 'G', Taarray = 'H', Tpointer = 'P', Tfunction = 'F', Tident = 'I', Tclass = 'C', Tstruct = 'S', Tenum = 'E', Ttypedef = 'T', Tdelegate = 'D', } // return the TypeInfo for a primitive type and null otherwise. // This is required since for arrays of ints we only have the mangled // char to work from. If arrays always subclassed TypeInfo_Array this // routine could go away. private TypeInfo primitiveTypeInfo(Mangle m) { TypeInfo ti; switch (m) { case Mangle.Tvoid: ti = typeid(void);break; case Mangle.Tbit: ti = typeid(bit);break; case Mangle.Tbool: ti = typeid(bool);break; case Mangle.Tbyte: ti = typeid(byte);break; case Mangle.Tubyte: ti = typeid(ubyte);break; case Mangle.Tshort: ti = typeid(short);break; case Mangle.Tushort: ti = typeid(ushort);break; case Mangle.Tint: ti = typeid(int);break; case Mangle.Tuint: ti = typeid(uint);break; case Mangle.Tlong: ti = typeid(long);break; case Mangle.Tulong: ti = typeid(ulong);break; case Mangle.Tfloat: ti = typeid(float);break; case Mangle.Tdouble: ti = typeid(double);break; case Mangle.Treal: ti = typeid(real);break; case Mangle.Tifloat: ti = typeid(ifloat);break; case Mangle.Tidouble: ti = typeid(idouble);break; case Mangle.Tireal: ti = typeid(ireal);break; case Mangle.Tcfloat: ti = typeid(cfloat);break; case Mangle.Tcdouble: ti = typeid(cdouble);break; case Mangle.Tcreal: ti = typeid(creal);break; case Mangle.Tchar: ti = typeid(char);break; case Mangle.Twchar: ti = typeid(wchar);break; case Mangle.Tdchar: ti = typeid(dchar); default: ti = null; } return ti; } /************************************ * Interprets variadic argument list pointed to by argptr whose types are given * by arguments[], formats them according to embedded format strings in the * variadic argument list, and sends the resulting characters to putc. * * The variadic arguments are consumed in order. * Each is formatted into a sequence of chars, using the default format * specification for its type, and the * characters are sequentially passed to putc. * If a char[], wchar[], or dchar[] * argument is encountered, it is interpreted as a format string. As many * arguments as specified in the format string are consumed and formatted * according to the format specifications in that string and passed to putc. If * there are too few remaining arguments, a FormatError is thrown. If there are * more remaining arguments than needed by the format specification, the default * processing of arguments resumes until they are all consumed. * * Params: * putc = Output is sent do this delegate, character by character. * arguments = Array of TypeInfo's, one for each argument to be formatted. * argptr = Points to variadic argument list. * * Throws: * Mismatched arguments and formats result in a FormatError being thrown. * * Format_String: * $(I Format strings) * consist of characters interspersed with * $(I format specifications). Characters are simply copied * to the output (such as putc) after any necessary conversion * to the corresponding UTF-8 sequence. * * A $(I format specification) starts with a '%' character, * and has the following grammar: 
$(I FormatSpecification):
    $(B '%%')
    $(B '%') $(I Flags) $(I Width) $(I Precision) $(I FormatChar)

$(I Flags):
    $(I empty)
    $(B '-') $(I Flags)
    $(B '+') $(I Flags)
    $(B '#') $(I Flags)
    $(B '0') $(I Flags)
    $(B ' ') $(I Flags)

$(I Width):
    $(I empty)
    $(I Integer)
    $(B '*')

$(I Precision):
    $(I empty)
    $(B '.')
    $(B '.') $(I Integer)
    $(B '.*')

$(I Integer):
    $(I Digit)
    $(I Digit) $(I Integer)

$(I Digit):
    $(B '0')
    $(B '1')
    $(B '2')
    $(B '3')
    $(B '4')
    $(B '5')
    $(B '6')
    $(B '7')
    $(B '8')
    $(B '9')

$(I FormatChar):
    $(B 's')
    $(B 'b')
    $(B 'd')
    $(B 'o')
    $(B 'x')
    $(B 'X')
    $(B 'e')
    $(B 'E')
    $(B 'f')
    $(B 'F')
    $(B 'g')
    $(B 'G')
    $(B 'a')
    $(B 'A')
$(I Flags)
$(B '-')
Left justify the result in the field. It overrides any $(B 0) flag.
$(B '+')
Prefix positive numbers in a signed conversion with a $(B +). It overrides any $(I space) flag.
$(B '#')
Use alternative formatting:
For $(B 'o'):
Add to precision as necessary so that the first digit of the octal formatting is a '0', even if both the argument and the $(I Precision) are zero.
For $(B 'x') ($(B 'X')):
If non-zero, prefix result with $(B 0x) ($(B 0X)).
For floating point formatting:
Always insert the decimal point.
For $(B 'g') ($(B 'G')):
Do not elide trailing zeros.
$(B '0')
For integer and floating point formatting when not nan or infinity, use leading zeros to pad rather than spaces. Ignore if there's a $(I Precision).
$(B ' ')
Prefix positive numbers in a signed conversion with a space.
$(I Width)
Specifies the minimum field width. If the width is a $(B *), the next argument, which must be of type $(B int), is taken as the width. If the width is negative, it is as if the $(B -) was given as a $(I Flags) character.
$(I Precision)
Gives the precision for numeric conversions. If the precision is a $(B *), the next argument, which must be of type $(B int), is taken as the precision. If it is negative, it is as if there was no $(I Precision).
$(I FormatChar)
$(B 's')
The corresponding argument is formatted in a manner consistent with its type:
$(B bool)
The result is 'true' or 'false'.
integral types
The $(B %d) format is used.
floating point types
The $(B %g) format is used.
string types
The result is the string converted to UTF-8. A $(I Precision) specifies the maximum number of characters to use in the result.
classes derived from $(B Object)
The result is the string returned from the class instance's $(B .toString()) method. A $(I Precision) specifies the maximum number of characters to use in the result.
non-string static and dynamic arrays
The result is [s0, s1, ...] where sk is the kth element formatted with the default format.
$(B 'b','d','o','x','X')
The corresponding argument must be an integral type and is formatted as an integer. If the argument is a signed type and the $(I FormatChar) is $(B d) it is converted to a signed string of characters, otherwise it is treated as unsigned. An argument of type $(B bool) is formatted as '1' or '0'. The base used is binary for $(B b), octal for $(B o), decimal for $(B d), and hexadecimal for $(B x) or $(B X). $(B x) formats using lower case letters, $(B X) uppercase. If there are fewer resulting digits than the $(I Precision), leading zeros are used as necessary. If the $(I Precision) is 0 and the number is 0, no digits result.
$(B 'e','E')
A floating point number is formatted as one digit before the decimal point, $(I Precision) digits after, the $(I FormatChar), ±, followed by at least a two digit exponent: $(I d.dddddd)e$(I ±dd). If there is no $(I Precision), six digits are generated after the decimal point. If the $(I Precision) is 0, no decimal point is generated.
$(B 'f','F')
A floating point number is formatted in decimal notation. The $(I Precision) specifies the number of digits generated after the decimal point. It defaults to six. At least one digit is generated before the decimal point. If the $(I Precision) is zero, no decimal point is generated.
$(B 'g','G')
A floating point number is formatted in either $(B e) or $(B f) format for $(B g); $(B E) or $(B F) format for $(B G). The $(B f) format is used if the exponent for an $(B e) format is greater than -5 and less than the $(I Precision). The $(I Precision) specifies the number of significant digits, and defaults to one. Trailing zeros are elided after the decimal point, if the fractional part is zero then no decimal point is generated.
$(B 'a','A')
A floating point number is formatted in hexadecimal exponential notation 0x$(I h.hhhhhh)p$(I ±d). There is one hexadecimal digit before the decimal point, and as many after as specified by the $(I Precision). If the $(I Precision) is zero, no decimal point is generated. If there is no $(I Precision), as many hexadecimal digits as necessary to exactly represent the mantissa are generated. The exponent is written in as few digits as possible, but at least one, is in decimal, and represents a power of 2 as in $(I h.hhhhhh)*2$(I ±d). The exponent for zero is zero. The hexadecimal digits, x and p are in upper case if the $(I FormatChar) is upper case.
Floating point NaN's are formatted as $(B nan) if the $(I FormatChar) is lower case, or $(B NAN) if upper. Floating point infinities are formatted as $(B inf) or $(B infinity) if the $(I FormatChar) is lower case, or $(B INF) or $(B INFINITY) if upper.
Example: ------------------------- import std.c.stdio; import std.format; void formattedPrint(...) { void putc(char c) { fputc(c, stdout); } std.format.doFormat(&putc, _arguments, _argptr); } ... int x = 27; // prints 'The answer is 27:6' formattedPrint("The answer is %s:", x, 6); ------------------------ */ void doFormat(void delegate(dchar) putc, TypeInfo[] arguments, va_list argptr) { int j; TypeInfo ti; Mangle m; uint flags; int field_width; int precision; enum : uint { FLdash = 1, FLplus = 2, FLspace = 4, FLhash = 8, FLlngdbl = 0x20, FL0pad = 0x40, FLprecision = 0x80, } void formatArg(char fc) { bool vbit; ulong vnumber; char vchar; dchar vdchar; Object vobject; real vreal; creal vcreal; Mangle m2; int signed = 0; uint base = 10; int uc; char[ulong.sizeof * 8] tmpbuf; // long enough to print long in binary char* prefix = ""; char[] s; void putstr(char[] s) { //printf("flags = x%x\n", flags); int prepad = 0; int postpad = 0; int padding = field_width - (strlen(prefix) + s.length); if (padding > 0) { if (flags & FLdash) postpad = padding; else prepad = padding; } if (flags & FL0pad) { while (*prefix) putc(*prefix++); while (prepad--) putc('0'); } else { while (prepad--) putc(' '); while (*prefix) putc(*prefix++); } foreach (dchar c; s) putc(c); while (postpad--) putc(' '); } void putreal(real v) { //printf("putreal %Lg\n", vreal); switch (fc) { case 's': fc = 'g'; break; case 'f', 'F', 'e', 'E', 'g', 'G', 'a', 'A': break; default: //printf("fc = '%c'\n", fc); Lerror: throw new FormatError("floating"); } version (DigitalMarsC) { int sl; char[] fbuf = tmpbuf; if (!(flags & FLprecision)) precision = 6; while (1) { sl = fbuf.length; prefix = (*__pfloatfmt)(fc, flags | FLlngdbl, precision, &v, cast(char*)fbuf, &sl, field_width); if (sl != -1) break; sl = fbuf.length * 2; fbuf = (cast(char*)alloca(sl * char.sizeof))[0 .. sl]; } putstr(fbuf[0 .. sl]); } else { int sl; char[] fbuf = tmpbuf; char[12] format; format[0] = '%'; int i = 1; if (flags & FLdash) format[i++] = '-'; if (flags & FLplus) format[i++] = '+'; if (flags & FLspace) format[i++] = ' '; if (flags & FLhash) format[i++] = '#'; if (flags & FL0pad) format[i++] = '0'; format[i + 0] = '*'; format[i + 1] = '.'; format[i + 2] = '*'; format[i + 3] = 'L'; format[i + 4] = fc; format[i + 5] = 0; if (!(flags & FLprecision)) precision = -1; while (1) { int n; sl = fbuf.length; n = snprintf(fbuf, sl, format, field_width, precision, v); //printf("format = '%s', n = %d\n", cast(char*)format, n); if (n >= 0 && n < sl) { sl = n; break; } if (n < 0) sl = sl * 2; else sl = n + 1; fbuf = (cast(char*)alloca(sl * char.sizeof))[0 .. sl]; } putstr(fbuf[0 .. sl]); } return; } void putArray(void* p, size_t len, TypeInfo ti) { putc('['); size_t tsize = ti.tsize(); while (len--) { doFormat(putc, (&ti)[0 .. 1], p); p += tsize; if (len > 0) putc(','); } putc(']'); } //printf("formatArg(fc = '%c', m = '%c')\n", fc, m); switch (m) { case Mangle.Tbit: case Mangle.Tbool: vbit = va_arg!(bool)(argptr); if (fc != 's') { vnumber = vbit; goto Lnumber; } putstr(vbit ? "true" : "false"); return; case Mangle.Tchar: vchar = va_arg!(char)(argptr); if (fc != 's') { vnumber = vchar; goto Lnumber; } L2: putstr((&vchar)[0 .. 1]); return; case Mangle.Twchar: vdchar = va_arg!(wchar)(argptr); goto L1; case Mangle.Tdchar: vdchar = va_arg!(dchar)(argptr); L1: if (fc != 's') { vnumber = vdchar; goto Lnumber; } if (vdchar <= 0x7F) { vchar = cast(char)vdchar; goto L2; } else { if (!isValidDchar(vdchar)) throw new UtfException("invalid dchar in format", 0); char[4] vbuf; putstr(toUTF8(vbuf, vdchar)); } return; case Mangle.Tbyte: signed = 1; vnumber = va_arg!(byte)(argptr); goto Lnumber; case Mangle.Tubyte: vnumber = va_arg!(ubyte)(argptr); goto Lnumber; case Mangle.Tshort: signed = 1; vnumber = va_arg!(short)(argptr); goto Lnumber; case Mangle.Tushort: vnumber = va_arg!(ushort)(argptr); goto Lnumber; case Mangle.Tint: signed = 1; vnumber = va_arg!(int)(argptr); goto Lnumber; case Mangle.Tuint: Luint: vnumber = va_arg!(uint)(argptr); goto Lnumber; case Mangle.Tlong: signed = 1; vnumber = va_arg!(long)(argptr); goto Lnumber; case Mangle.Tulong: Lulong: vnumber = va_arg!(ulong)(argptr); goto Lnumber; case Mangle.Tclass: vobject = va_arg!(Object)(argptr); s = vobject.toString(); goto Lputstr; case Mangle.Tpointer: vnumber = cast(ulong)va_arg!(void*)(argptr); flags |= FL0pad; if (!(flags & FLprecision)) { flags |= FLprecision; precision = (void*).sizeof; } base = 16; goto Lnumber; case Mangle.Tfloat: case Mangle.Tifloat: if (fc == 'x' || fc == 'X') goto Luint; vreal = va_arg!(float)(argptr); goto Lreal; case Mangle.Tdouble: case Mangle.Tidouble: if (fc == 'x' || fc == 'X') goto Lulong; vreal = va_arg!(double)(argptr); goto Lreal; case Mangle.Treal: case Mangle.Tireal: vreal = va_arg!(real)(argptr); goto Lreal; case Mangle.Tcfloat: vcreal = va_arg!(cfloat)(argptr); goto Lcomplex; case Mangle.Tcdouble: vcreal = va_arg!(cdouble)(argptr); goto Lcomplex; case Mangle.Tcreal: vcreal = va_arg!(creal)(argptr); goto Lcomplex; case Mangle.Tarray: if (ti.classinfo.name.length == 14 && ti.classinfo.name[9..14] == "Array") { // array of non-primitive types void[] va = va_arg!(void[])(argptr); putArray(va.ptr, va.length, (cast(TypeInfo_Array)ti).next); return; } m2 = cast(Mangle)ti.classinfo.name[10]; switch (m2) { case Mangle.Tchar: s = va_arg!(char[])(argptr); goto Lputstr; case Mangle.Twchar: wchar[] sw = va_arg!(wchar[])(argptr); s = toUTF8(sw); goto Lputstr; case Mangle.Tdchar: dchar[] sd = va_arg!(dchar[])(argptr); s = toUTF8(sd); Lputstr: if (fc != 's') throw new FormatError("string"); if (flags & FLprecision && precision < s.length) s = s[0 .. precision]; putstr(s); break; default: TypeInfo ti2 = primitiveTypeInfo(m2); if (!ti2) goto Lerror; void[] va = va_arg!(void[])(argptr); putArray(va.ptr, va.length, ti2); } return; case Mangle.Ttypedef: ti = (cast(TypeInfo_Typedef)ti).base; m = cast(Mangle)ti.classinfo.name[9]; formatArg(fc); return; default: goto Lerror; } Lnumber: switch (fc) { case 's': case 'd': if (signed) { if (cast(long)vnumber < 0) { prefix = "-"; vnumber = -vnumber; } else if (flags & FLplus) prefix = "+"; else if (flags & FLspace) prefix = " "; } break; case 'b': signed = 0; base = 2; break; case 'o': signed = 0; base = 8; break; case 'X': uc = 1; if (flags & FLhash && vnumber) prefix = "0X"; signed = 0; base = 16; break; case 'x': if (flags & FLhash && vnumber) prefix = "0x"; signed = 0; base = 16; break; default: goto Lerror; } if (flags & FLprecision && fc != 'p') flags &= ~FL0pad; if (vnumber < 10) { if (vnumber == 0 && precision == 0 && flags & FLprecision && !(fc == 'o' && flags & FLhash)) { putstr(null); return; } if (vnumber < base) { vchar = '0' + vnumber; goto L2; } } int n = tmpbuf.length; char c; int hexoffset = uc ? ('A' - ('9' + 1)) : ('a' - ('9' + 1)); while (vnumber) { c = (vnumber % base) + '0'; if (c > '9') c += hexoffset; vnumber /= base; tmpbuf[--n] = c; } if (tmpbuf.length - n < precision && precision < tmpbuf.length) { int m = tmpbuf.length - precision; tmpbuf[m .. n] = '0'; n = m; } else if (flags & FLhash && fc == 'o') prefix = "0"; putstr(tmpbuf[n .. tmpbuf.length]); return; Lreal: putreal(vreal); return; Lcomplex: putreal(vcreal.re); putc('+'); putreal(vcreal.im); putc('i'); return; Lerror: throw new FormatError("formatArg"); } for (j = 0; j < arguments.length; ) { ti = arguments[j++]; //printf("test1: '%.*s' %d\n", ti.classinfo.name, ti.classinfo.name.length); //ti.print(); if (ti.classinfo.name.length < 10) goto Lerror; m = cast(Mangle)ti.classinfo.name[9]; if (m == Mangle.Tarray) { Mangle m2 = cast(Mangle)ti.classinfo.name[10]; char[] fmt; // format string wchar[] wfmt; dchar[] dfmt; /* For performance reasons, this code takes advantage of the * fact that most format strings will be ASCII, and that the * format specifiers are always ASCII. This means we only need * to deal with UTF in a couple of isolated spots. */ switch (m2) { case Mangle.Tchar: fmt = va_arg!(char[])(argptr); break; case Mangle.Twchar: wfmt = va_arg!(wchar[])(argptr); fmt = toUTF8(wfmt); break; case Mangle.Tdchar: dfmt = va_arg!(dchar[])(argptr); fmt = toUTF8(dfmt); break; default: formatArg('s'); continue; } for (size_t i = 0; i < fmt.length; ) { dchar c = fmt[i++]; dchar getFmtChar() { // Valid format specifier characters will never be UTF if (i == fmt.length) throw new FormatError("invalid specifier"); return fmt[i++]; } int getFmtInt() { int n; while (1) { n = n * 10 + (c - '0'); if (n < 0) // overflow throw new FormatError("int overflow"); c = getFmtChar(); if (c < '0' || c > '9') break; } return n; } int getFmtStar() { Mangle m; TypeInfo ti; if (j == arguments.length) throw new FormatError("too few arguments"); ti = arguments[j++]; m = cast(Mangle)ti.classinfo.name[9]; if (m != Mangle.Tint) throw new FormatError("int argument expected"); return va_arg!(int)(argptr); } if (c != '%') { if (c > 0x7F) // if UTF sequence { i--; // back up and decode UTF sequence c = std.utf.decode(fmt, i); } Lputc: putc(c); continue; } // Get flags {-+ #} flags = 0; while (1) { c = getFmtChar(); switch (c) { case '-': flags |= FLdash; continue; case '+': flags |= FLplus; continue; case ' ': flags |= FLspace; continue; case '#': flags |= FLhash; continue; case '0': flags |= FL0pad; continue; case '%': if (flags == 0) goto Lputc; default: break; } break; } // Get field width field_width = 0; if (c == '*') { field_width = getFmtStar(); if (field_width < 0) { flags |= FLdash; field_width = -field_width; } c = getFmtChar(); } else if (c >= '0' && c <= '9') field_width = getFmtInt(); if (flags & FLplus) flags &= ~FLspace; if (flags & FLdash) flags &= ~FL0pad; // Get precision precision = 0; if (c == '.') { flags |= FLprecision; //flags &= ~FL0pad; c = getFmtChar(); if (c == '*') { precision = getFmtStar(); if (precision < 0) { precision = 0; flags &= ~FLprecision; } c = getFmtChar(); } else if (c >= '0' && c <= '9') precision = getFmtInt(); } if (j == arguments.length) goto Lerror; ti = arguments[j++]; m = cast(Mangle)ti.classinfo.name[9]; if (c > 0x7F) // if UTF sequence goto Lerror; // format specifiers can't be UTF formatArg(cast(char)c); } } else { field_width = 0; flags = 0; precision = 0; formatArg('s'); } } return; Lerror: throw new FormatError(); } /* ======================== Unit Tests ====================================== */ unittest { int i; char[] s; debug(format) printf("std.format.format.unittest\n"); s = std.string.format("hello world! %s %s ", true, 57, 1_000_000_000, 'x', " foo"); assert(s == "hello world! true 57 1000000000x foo"); s = std.string.format(1.67, " %A ", -1.28, float.nan); /* The host C library is used to format floats. * C99 doesn't specify what the hex digit before the decimal point * is for %A. */ version (linux) assert(s == "1.67 -0XA.3D70A3D70A3D8P-3 nan"); else assert(s == "1.67 -0X1.47AE147AE147BP+0 nan"); s = std.string.format("%x %X", 0x1234AF, 0xAFAFAFAF); assert(s == "1234af AFAFAFAF"); s = std.string.format("%b %o", 0x1234AF, 0xAFAFAFAF); assert(s == "100100011010010101111 25753727657"); s = std.string.format("%d %s", 0x1234AF, 0xAFAFAFAF); assert(s == "1193135 2947526575"); s = std.string.format("%s", 1.2 + 3.4i); assert(s == "1.2+3.4i"); s = std.string.format("%x %X", 1.32, 6.78f); assert(s == "3ff51eb851eb851f 40D8F5C3"); s = std.string.format("%#06.*f",2,12.345); assert(s == "012.35"); s = std.string.format("%#0*.*f",6,2,12.345); assert(s == "012.35"); s = std.string.format("%7.4g:", 12.678); assert(s == " 12.68:"); s = std.string.format("%04f|%05d|%#05x|%#5x",-4.,-10,1,1); assert(s == "-4.000000|-0010|0x001| 0x1"); i = -10; s = std.string.format("%d|%3d|%03d|%1d|%01.4f",i,i,i,i,cast(double) i); assert(s == "-10|-10|-10|-10|-10.0000"); i = -5; s = std.string.format("%d|%3d|%03d|%1d|%01.4f",i,i,i,i,cast(double) i); assert(s == "-5| -5|-05|-5|-5.0000"); i = 0; s = std.string.format("%d|%3d|%03d|%1d|%01.4f",i,i,i,i,cast(double) i); assert(s == "0| 0|000|0|0.0000"); i = 5; s = std.string.format("%d|%3d|%03d|%1d|%01.4f",i,i,i,i,cast(double) i); assert(s == "5| 5|005|5|5.0000"); i = 10; s = std.string.format("%d|%3d|%03d|%1d|%01.4f",i,i,i,i,cast(double) i); assert(s == "10| 10|010|10|10.0000"); s = std.string.format("%.0d", 0); assert(s == ""); s = std.string.format("%.g", .34); assert(s == "0.3"); s = std.string.format("%.0g", .34); assert(s == "0.3"); s = std.string.format("%.2g", .34); assert(s == "0.34"); s = std.string.format("%0.0008f", 1e-08); assert(s == "0.00000001"); s = std.string.format("%0.0008f", 1e-05); assert(s == "0.00001000"); s = "helloworld"; char[] r; r = std.string.format("%.2s", s[0..5]); assert(r == "he"); r = std.string.format("%.20s", s[0..5]); assert(r == "hello"); r = std.string.format("%8s", s[0..5]); assert(r == " hello"); int[] arr = new int[4]; arr[0] = 100; arr[1] = -999; arr[3] = 0; r = std.string.format(arr); assert(r == "[100,-999,0,0]"); r = std.string.format("%s",arr); assert(r == "[100,-999,0,0]"); char[][] arr2 = new char[][4]; arr2[0] = "hello"; arr2[1] = "world"; arr2[3] = "foo"; r = std.string.format(arr2); assert(r == "[hello,world,,foo]"); }