类型转换之字符串转int型

函数原型：
int atoi(

   const char *str 
);
int _wtoi(
   const wchar_t *str 
);

包含头文件：#include <stdlib.h>

函数参数：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.超过最大值返回LONG_MAX,小于最小值返回LONG_MIN.

示例程序：

#include "stdafx.h"
#include 
#include 

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

 // An example of the atoi function.
 str = "  -3536 ";
 value = atoi( str );
 printf( "Function: atoi( \"%s\" ) = %d\n", str, value );

 // Another example of the atoi function.
 str = "41412765";
 value = atoi( str );
 printf( "Function: atoi( \"%s\" ) = %d\n", str, value );

 // Another example of the atoi function 
 // with an overflow condition occuring.
 str = "5556402735171707160320";
 value = atoi( str );
 printf( "Function: atoi( \"%s\" ) = %d\n", str, value );
 if (errno == ERANGE)
 {
 printf("Overflow condition occurred.\n");
 }
 //////////////////////////////////////////
 wstr = L"  -36309 ";
 value = _wtoi( wstr );
 printf( "Function: _wtoi( \"%ws\" ) = %d\n", wstr, value );

 // Another example of the _wtoi function.
 wstr = L"124544667";
 value = _wtoi( wstr );
 printf( "Function: _wtoi( \"%ws\" ) = %d\n", wstr, value );

 // Another example of the _wtoi function 
 // with an overflow condition occuring.
 wstr = L"548556564171707160320";
 value = _wtoi( wstr );
 printf( "Function: _wtoi( \"%ws\" ) = %d\n", wstr, value );
 if (errno == ERANGE)
 {
 printf("Overflow condition occurred.\n");
 }

 getchar();
 return 0;
}
运行结果：

另外，字符串转长整型介绍：http://blog.chinaunix.net/uid-29121609-id-4030955.html

字符串转换为double型：http://blog.chinaunix.net/uid-29121609-id-4031108.html