百科狗sprintf() - 返回格式化字符串 - php 字符串函数
sprintf()
(PHP 4, PHP 5, PHP 7)
返回格式化字符串
说明
sprintf(string $format[,mixed $...]): string返回根据格式化字符串生成的字符串$format.
参数
$formatThe format string is composed of zero or more directives: ordinary characters(excluding%)that are copied directly to the result andconversion specifications, each of which results in fetching its own parameter.
A conversion specification follows this prototype:%[argnum$][flags][width][.precision]specifier.
Argnum
An integer followed by a dollar sign$, to specify which number argument to treat in the conversion.
| Flag | 说明 |
|---|---|
| - | Left-justify within the given field width; Right justification is the default |
| + | Prefix positive numbers with a plus sign+; Default only negative are prefixed with a negative sign. |
| (space) | Pads the result with spaces. This is the default. |
| 0 | Only left-pads numbers with zeros.Withsspecifiers this can also right-pad with zeros. |
| '(char) | Pads the result with the character(char). |
Width
An integer that says how many characters(minimum)this conversion should result in.
Precision
A period.followed by an integer who's meaning depends on the specifier:
- Fore,E,fandFspecifiers: this is the number of digits to be printed after the decimal point(by default, this is 6).
- ForgandGspecifiers: this is the maximum number of significant digits to be printed.
- Forsspecifier: it acts as a cutoff point, setting a maximum character limit to the string.
Note:Attempting to use a position specifier greater thanPHP_INT_MAXwill generate warnings.
| Specifier | 说明 |
|---|---|
| % | A literal percent character. No argument is required. |
| b | The argument is treated as an integer and presented as a binary number. |
| c | The argument is treated as an integer and presented as the character with that ASCII. |
| d | The argument is treated as an integer and presented as a(signed)decimal number. |
| e | The argument is treated as scientific notation(e.g. 1.2e+2). The precision specifier stands for the number of digits after the decimal point since PHP 5.2.1. In earlier versions, it was taken as number of significant digits(one less). |
| E | Like theespecifier but uses uppercase letter(e.g. 1.2E+2). |
| f | The argument is treated as a float and presented as a floating-point number(locale aware). |
| F | The argument is treated as a float and presented as a floating-point number(non-locale aware). Available as of PHP 5.0.3. |
| g | General format. Let P equal the precision if nonzero, 6 if the precision is omitted, or 1 if the precision is zero. Then, if a conversion with style E would have an exponent of X: If P > X ≥−4, the conversion is with style f and precision P −(X + 1). Otherwise, the conversion is with style e and precision P − 1. |
| G | Like thegspecifier but usesEandF. |
| o | The argument is treated as an integer and presented as an octal number. |
| s | The argument is treated and presented as a string. |
| u | The argument is treated as an integer and presented as an unsigned decimal number. |
| x | The argument is treated as an integer and presented as a hexadecimal number(with lowercase letters). |
| X | The argument is treated as an integer and presented as a hexadecimal number(with uppercase letters). |
Thectype specifier ignores padding and width
WarningAttempting to use a combination of the string and width specifiers with character sets that require more than one byte per character may result in unexpected results
Variables will be co-erced to a suitable type for the specifier:
| Type | Specifiers |
|---|---|
| string | s |
| integer | d,u,c,o,x,X,b |
| double | g,G,e,E,f,F |
返回值
Returns a string produced according to the formatting string$format,或者在失败时返回FALSE.
范例
Argument swapping
The format string supports argument numbering/swapping.
以上例程会输出：
There are 5 monkeys in the tree
However imagine we are creating a format string in a separate file, commonly because we would like to internationalize it and we rewrite it as:
We now have a problem. The order of the placeholders in the format string does not match the order of the arguments in the code. We would like to leave the code as is and simply indicate in the format string which arguments the placeholders refer to. We would write the format string like this instead:
An added benefit is that placeholders can be repeated without adding more arguments in the code.
When using argument swapping,then$position specifiermust come immediately after the percent sign(%), before any other specifiers, as shown below.
Specifying padding character
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