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 <stdlib.h>#include <errno.h>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