类型转换之字符串转double型

函数原型:
double atof(

   const char *str 
);
double _wtof(
   const wchar_t *str 
);

包含头文件：#include 

参数说明：str:要转换的字符串。

函数返回值：成功返回转换后的数值，失败返回0.0.

示例程序：
#include "stdafx.h"
#include

int _tmain(int argc, _TCHAR* argv[])
{
char    *str = NULL;
wchar_t *wstr = NULL;
double  value = 0;

// An example of the atof function
// using leading and training spaces.
str = "  5676402735171707160320 ";
value = atof( str );
printf( "Function: atof( \"%s\" ) = %e\n", str, value );

// Another example of the atof function
// using the 'd' exponential formatting keyword.
str = "6.1412764583d210";
value = atof( str );
printf( "Function: atof( \"%s\" ) = %e\n", str, value );

// An example of the atof function
// using the 'e' exponential formatting keyword.
str = "  -7306.12E-15";
value = atof( str );
printf( "Function: atof( \"%s\" ) = %e\n", str, value );

////////////////////////////////
// An example of the _wtof function
// using leading and training spaces.
wstr = L"  6786402735171707160320 ";
value = _wtof( wstr );
printf( "Function: atof( \"%ws\" ) = %e\n", wstr, value );

// Another example of the _wtof function
// using the 'd' exponential formatting keyword.
wstr = L"8.6512764583d210";
value = _wtof( wstr );
printf( "Function: atof( \"%ws\" ) = %e\n", wstr, value );


// An example of the _wtof function
// using the 'e' exponential formatting keyword.
wstr = L"  -6709.12E-13";
value = _wtof( wstr );
printf( "Function: atof( \"%ws\" ) = %e\n", wstr, value );


getchar();
return 0;
}
运行结果：

字符串转换为长整型：http://blog.chinaunix.net/uid-29121609-id-4030955.html
字符串转换为整型：http://blog.chinaunix.net/uid-29121609-id-4031083.html