c语言atof函数_atof（）函数与C ++中的示例-蒲公英云

c语言atof函数_atof（）函数与C ++中的示例

c语言atof函数

C ++ atof()函数 (C++ atof() function)

atof() function is a library function of cstdlib header. It is used to convert the given string value to the double value. It accepts a string containing a floating-point number and returns its double value.

atof()函数是cstdlib标头的库函数。它用于将给定的字符串值转换为双精度值。它接受包含浮点数的字符串，并返回其双精度值。

Syntax of atof() function:

atof()函数的语法：

C++11:

C ++ 11：

double atof (const char* str);

Parameter(s):

参数：

str – represents a string containing a floating-point number.

str –表示包含浮点数的字符串。

Return value:

返回值：

The return type of this function is double, it returns the double converted value.

该函数的返回类型为double ，它返回double转换后的值。

Example:

例：

Input:
    str = "123.456";
    Function call:
    atof(str);
    Output:
    123.456

C ++代码演示atof()函数的示例 (C++ code to demonstrate the example of atof() function)

// C++ code to demonstrate the example of
// atof() function
#include <iostream>
#include <cstdlib>
#include <string.h>
using namespace std;
// main() section
int main()
{
    char str[50];
    strcpy(str, "123.456");
    cout << "atof(\"" << str << "\"): " << atof(str) << endl;
    strcpy(str, "-123.456");
    cout << "atof(\"" << str << "\"): " << atof(str) << endl;
    strcpy(str, "0.123456");
    cout << "atof(\"" << str << "\"): " << atof(str) << endl;
    strcpy(str, "-0.123456");
    cout << "atof(\"" << str << "\"): " << atof(str) << endl;
    strcpy(str, "12345678.123456");
    cout << "atof(\"" << str << "\"): " << atof(str) << endl;
    strcpy(str, "-12345678.123456");
    cout << "atof(\"" << str << "\"): " << atof(str) << endl;
    return 0;
}

Output

输出量

atof("123.456"): 123.456
atof("-123.456"): -123.456
atof("0.123456"): 0.123456
atof("-0.123456"): -0.123456
atof("12345678.123456"): 1.23457e+07
atof("-12345678.123456"): -1.23457e+07