std::ios_base::setf
科技促进发展：监督办[医]基地：SETF
| fmtflags setf( fmtflags flags | (1) | |
|---|---|---|
| fmtflags setf( fmtflags flags, fmtflags mask | (2) | |
将格式化标志设置为指定的设置。
1%29设置由flags有效地执行以下操作fl = fl | flags何地fl定义内部格式标志的状态。
2%29清除下面的格式标志mask，并将已清除的标志设置为flags有效地执行以下操作fl = (fl & ~mask) | (flags & mask)何地fl定义内部格式标志的状态。
参数
| flags, mask | - | new formatting setting. mask defines which flags can be altered, flags defines which flags of those to be altered should be set (others will be cleared). Both parameters can be a combination of the following constants: Constant Explanation dec use decimal base for integer I/O: see std::dec oct use octal base for integer I/O: see std::oct hex use hexadecimal base for integer I/O: see std::hex basefield dec|oct|hex|0. Useful for masking operations left left adjustment (adds fill characters to the right): see std::left right right adjustment (adds fill characters to the left): see std::right internal internal adjustment (adds fill characters to the internal designated point): see std::internal adjustfield left|right|internal. Useful for masking operations scientific generate floating point types using scientific notation, or hex notation if combined with fixed: see std::scientific fixed generate floating point types using fixed notation, or hex notation if combined with scientific: see std::fixed floatfield scientific|fixed|(scientific|fixed)|0. Useful for masking operations boolalpha insert and extract bool type in alphanumeric format: see std::boolalpha showbase generate a prefix indicating the numeric base for integer output, require the currency indicator in monetary I/O: see std::showbase showpoint generate a decimal-point character unconditionally for floating-point number output: see std::showpoint showpos generate a + character for non-negative numeric output: see std::showpos skipws skip leading whitespace before certain input operations: see std::skipws unitbuf flush the output after each output operation: see std::unitbuf uppercase replace certain lowercase letters with their uppercaseequivalents in certain output output operations: see std::uppercase | Constant | Explanation | dec | use decimal base for integer I/O: see std::dec | oct | use octal base for integer I/O: see std::oct | hex | use hexadecimal base for integer I/O: see std::hex | basefield | dec|oct|hex|0. Useful for masking operations | left | left adjustment (adds fill characters to the right): see std::left | right | right adjustment (adds fill characters to the left): see std::right | internal | internal adjustment (adds fill characters to the internal designated point): see std::internal | adjustfield | left|right|internal. Useful for masking operations | scientific | generate floating point types using scientific notation, or hex notation if combined with fixed: see std::scientific | fixed | generate floating point types using fixed notation, or hex notation if combined with scientific: see std::fixed | floatfield | scientific|fixed|(scientific|fixed)|0. Useful for masking operations | boolalpha | insert and extract bool type in alphanumeric format: see std::boolalpha | showbase | generate a prefix indicating the numeric base for integer output, require the currency indicator in monetary I/O: see std::showbase | showpoint | generate a decimal-point character unconditionally for floating-point number output: see std::showpoint | showpos | generate a + character for non-negative numeric output: see std::showpos | skipws | skip leading whitespace before certain input operations: see std::skipws | unitbuf | flush the output after each output operation: see std::unitbuf | uppercase | replace certain lowercase letters with their uppercaseequivalents in certain output output operations: see std::uppercase |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Constant | Explanation | |||||||||||||||||||||||||||||||||||||||
| dec | use decimal base for integer I/O: see std::dec | |||||||||||||||||||||||||||||||||||||||
| oct | use octal base for integer I/O: see std::oct | |||||||||||||||||||||||||||||||||||||||
| hex | use hexadecimal base for integer I/O: see std::hex | |||||||||||||||||||||||||||||||||||||||
| basefield | dec|oct|hex|0. Useful for masking operations | |||||||||||||||||||||||||||||||||||||||
| left | left adjustment (adds fill characters to the right): see std::left | |||||||||||||||||||||||||||||||||||||||
| right | right adjustment (adds fill characters to the left): see std::right | |||||||||||||||||||||||||||||||||||||||
| internal | internal adjustment (adds fill characters to the internal designated point): see std::internal | |||||||||||||||||||||||||||||||||||||||
| adjustfield | left|right|internal. Useful for masking operations | |||||||||||||||||||||||||||||||||||||||
| scientific | generate floating point types using scientific notation, or hex notation if combined with fixed: see std::scientific | |||||||||||||||||||||||||||||||||||||||
| fixed | generate floating point types using fixed notation, or hex notation if combined with scientific: see std::fixed | |||||||||||||||||||||||||||||||||||||||
| floatfield | scientific|fixed|(scientific|fixed)|0. Useful for masking operations | |||||||||||||||||||||||||||||||||||||||
| boolalpha | insert and extract bool type in alphanumeric format: see std::boolalpha | |||||||||||||||||||||||||||||||||||||||
| showbase | generate a prefix indicating the numeric base for integer output, require the currency indicator in monetary I/O: see std::showbase | |||||||||||||||||||||||||||||||||||||||
| showpoint | generate a decimal-point character unconditionally for floating-point number output: see std::showpoint | |||||||||||||||||||||||||||||||||||||||
| showpos | generate a + character for non-negative numeric output: see std::showpos | |||||||||||||||||||||||||||||||||||||||
| skipws | skip leading whitespace before certain input operations: see std::skipws | |||||||||||||||||||||||||||||||||||||||
| unitbuf | flush the output after each output operation: see std::unitbuf | |||||||||||||||||||||||||||||||||||||||
| uppercase | replace certain lowercase letters with their uppercaseequivalents in certain output output operations: see std::uppercase |
返回值
调用函数之前的格式标志。
例
二次
#include <iostream>
#include <iomanip>
const double PI = 3.1415926535;
int main()
{
const int WIDTH = 15;
std::cout.setf(std::ios::right //equivalent: cout << right;
std::cout << std::setw(WIDTH/2) << "radius"
<< std::setw(WIDTH) << "circumference" << '\n';
std::cout.setf(std::ios::fixed
for (double radius = 1; radius <= 6; radius += 0.5) {
std::cout << std::setprecision(1) << std::setw(WIDTH/2)
<< radius
<< std::setprecision(2) << std::setw(WIDTH)
<< (2 * PI * radius) << '\n';
}
}
二次
产出：
二次
radius circumference
1.0 6.28
1.5 9.42
2.0 12.57
2.5 15.71
3.0 18.85
3.5 21.99
4.0 25.13
4.5 28.27
5.0 31.42
5.5 34.56
6.0 37.70
二次
另见
| flags | manages format flags (public member function) |
|---|---|
| unsetf | clears specific format flag (public member function) |
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