format --這是包含文本字符串寫入stdout。它可以包含嵌入的格式在隨后的附加參數(shù)指定的值所取代的標(biāo)簽和格式化所要求。格式標(biāo)簽的原型是 %[flags][width][.precision][length]specifier, 它們?cè)敿?xì)的解釋如下：

specifier	輸出
c	Character.
d or i	Signed decimal integer
e	Scientific notation (mantissa/exponent) using e character
E	Scientific notation (mantissa/exponent) using E character
f	Decimal floating yiibai
g	Use the shorter of %e or %f.
G	Use the shorter of %E or %f
o	Signed octal
s	String of characters
u	Unsigned decimal integer
x	Unsigned hexadecimal integer
X	Unsigned hexadecimal integer (capital letters)
p	Yiibaier address
n	Nothing printed.
%	Character.

標(biāo)識(shí)	描述
-	Left-justify within the given field width; Right justification is the default (see width sub-specifier).
+	Forces to preceed the result with a plus or minus sign (+ or -) even for positive numbers. By default, only negative numbers are preceded with a - sign..
(space)	If no sign is going to be written, a blank space is inserted before the value.
#	Used with o, x or X specifiers the value is preceeded with 0, 0x or 0X respectively for values different than zero. Used with e, E and f, it forces the written output to contain a decimal yiibai even if no digits would follow. By default, if no digits follow, no decimal yiibai is written. Used with g or G the result is the same as with e or E but trailing zeros are not removed.
0	Left-pads the number with zeroes (0) instead of spaces, where padding is specified (see width sub-specifier).

width	描述
(number)	Minimum number of characters to be printed. If the value to be printed is shorter than this number, the result is padded with blank spaces. The value is not truncated even if the result is larger.
*	The width is not specified in the format string, but as an additional integer value argument preceding the argument that has to be formatted.

.precision	描述
.number	For integer specifiers (d, i, o, u, x, X): precision specifies the minimum number of digits to be written. If the value to be written is shorter than this number, the result is padded with leading zeros. The value is not truncated even if the result is longer. A precision of 0 means that no character is written for the value 0. For e, E and f specifiers: this is the number of digits to be printed after de decimal yiibai. For g and G specifiers: This is the maximum number of significant digits to be printed. For s: this is the maximum number of characters to be printed. By default all characters are printed until the ending null character is encountered. For c type: it has no effect. When no precision is specified, the default is 1. If the period is specified without an explicit value for precision, 0 is assumed.
.*	The precision is not specified in the format string, but as an additional integer value argument preceding the argument that has to be formatted.

.precision

描述

.number

For integer specifiers (d, i, o, u, x, X): precision specifies the minimum number of digits to be written. If the value to be written is shorter than this number, the result is padded with leading zeros. The value is not truncated even if the result is longer. A precision of 0 means that no character is written for the value 0. For e, E and f specifiers: this is the number of digits to be printed after de decimal yiibai. For g and G specifiers: This is the maximum number of significant digits to be printed. For s: this is the maximum number of characters to be printed. By default all characters are printed until the ending null character is encountered. For c type: it has no effect. When no precision is specified, the default is 1. If the period is specified without an explicit value for precision, 0 is assumed.

The precision is not specified in the format string, but as an additional integer value argument preceding the argument that has to be formatted.

length	描述
h	The argument is interpreted as a short int or unsigned short int (only applies to integer specifiers: i, d, o, u, x and X).
l	The argument is interpreted as a long int or unsigned long int for integer specifiers (i, d, o, u, x and X), and as a wide character or wide character string for specifiers c and s.
L	The argument is interpreted as a long double (only applies to floating yiibai specifiers: e, E, f, g and G).

additional arguments -- 根據(jù)格式字符串，函數(shù)可能會(huì)想到一系列的額外的參數(shù)，每個(gè)包含一個(gè)值，而不是插入的格式參數(shù)中指定的標(biāo)記每個(gè)％，如果有的話。應(yīng)該有相同數(shù)量的％預(yù)期值的標(biāo)簽的數(shù)量的這些參數(shù)。

返回值

如果成功，則返回寫入的字符總數(shù)。如果失敗，則返回一個(gè)負(fù)數(shù)。

實(shí)例

下面的例子演示了如何使用 printf() 函數(shù)。

#include <stdio.h>

int main ()
{
   int ch;

   for( ch = 75 ; ch <= 100; ch++ ) {
      printf("ASCII value = %d, Character = %c
", ch , ch );
   }

   return(0);
}

讓我們編譯和運(yùn)行上面的程序，這將產(chǎn)生以下結(jié)果：

ASCII value = 75, Character = K
ASCII value = 76, Character = L
ASCII value = 77, Character = M
ASCII value = 78, Character = N
ASCII value = 79, Character = O
ASCII value = 80, Character = P
ASCII value = 81, Character = Q
ASCII value = 82, Character = R
ASCII value = 83, Character = S
ASCII value = 84, Character = T
ASCII value = 85, Character = U
ASCII value = 86, Character = V
ASCII value = 87, Character = W
ASCII value = 88, Character = X
ASCII value = 89, Character = Y
ASCII value = 90, Character = Z
ASCII value = 91, Character = [
ASCII value = 92, Character = 
ASCII value = 93, Character = ]
ASCII value = 94, Character = ^
ASCII value = 95, Character = _
ASCII value = 96, Character = `
ASCII value = 97, Character = a
ASCII value = 98, Character = b
ASCII value = 99, Character = c
ASCII value = 100, Character = d

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