- 参考：http://www.cplusplus.com/reference/cstdio/printf/
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テキストが含まれているC文字列が書き込まれる 標準出力。
それは、必要に応じて埋め込み含むことができる 形式指定子 以降追加の引数で指定された値に置き換え、要求としてフォーマットされています。 形式指定子は 、このプロトタイプを以下： [ 以下の互換性ノートを参照 ] ％[フラグ] [幅] [精度] [長さ]指定子指定文字 がタイプとの解釈を定義するので、端部では、最も重要な構成要素でありますその対応する引数：
指定 出力 例 D または I 署名付き10進整数 392 で 符号なし10進整数 7235 インクルード 符号なしオクタル 610 バツ 符号なし進整数 7FA バツ 符号なし進整数（大文字） 7FA F 10進浮動小数点、小文字 392.65 F 10進浮動小数点、大文字 392.65 E 科学表記法（仮数/指数）、小文字 3.9265e + 2 E 科学表記法（仮数/指数）、大文字 3.9265E + 2 グラム ：最短表現使用 は％e または ％fは 392.65 G ：最短表現を使用し ％のE または ％Fを 392.65 A 進浮動小数点、小文字 -0xc.90fep-2 A 進浮動小数点、大文字 -0XC.90FEP-2 C キャラクター A S 文字の文字列 サンプル P ポインタアドレス B8000000 n個 何も印刷されません。
対応する引数はへのポインタでなければならない 署名int型。
これまでに書かれた文字の数は、指示位置に格納されます。％ A % followed by another % character will write a single % to the stream. %
The format specifier can also contain sub-specifiers: flags, width, .precision and modifiers (in that order), which are optional and follow these specifications:
flags description - 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 a, A, e, E, f, F, g or G it forces the written output to contain a decimal point even if no more digits follow. By default, if no digits follow, no decimal point is written.0 Left-pads the number with zeroes (0) instead of spaces when padding is specified (see width sub-specifier).
width description (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 description .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 a, A, e, E, f and F specifiers: this is the number of digits to be printed after the decimal point (by default, this is 6).
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.
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.
The length sub-specifier modifies the length of the data type. This is a chart showing the types used to interpret the corresponding arguments with and without length specifier (if a different type is used, the proper type promotion or conversion is performed, if allowed):
Note regarding thespecifiers length d i u o x X f F e E g G a A c s p n (none) int unsigned int double int char* void* int* hh signed char unsigned char signed char* h short int unsigned short int short int* l long int unsigned long int wint_t wchar_t* long int* ll long long int unsigned long long int long long int* j intmax_t uintmax_t intmax_t* z size_t size_t size_t* t ptrdiff_t ptrdiff_t ptrdiff_t* L long double cspecifier: it takes an int (or wint_t) as argument, but performs the proper conversion to a char value (or a wchar_t) before formatting it for output.
Note: Yellow rows indicate specifiers and sub-specifiers introduced by C99. See <cinttypes> for the specifiers for extended types. - ... (additional arguments)
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Depending on the format string, the function may expect a sequence of additional arguments, each containing a value to be used to replace a format specifier in the format string (or a pointer to a storage location, for n).
There should be at least as many of these arguments as the number of values specified in the format specifiers. Additional arguments are ignored by the function.
Return Value
On success, the total number of characters written is returned.
If a writing error occurs, the error indicator (ferror) is set and a negative number is returned.
If a multibyte character encoding error occurs while writing wide characters, errno is set to EILSEQ and a negative number is returned.
Example
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Output:
Characters: a A
Decimals: 1977 650000
Preceding with blanks: 1977
Preceding with zeros: 0000001977
Some different radices: 100 64 144 0x64 0144
floats: 3.14 +3e+000 3.141600E+000
Width trick: 10
A string |