_itoa _itow _itot atoi atof atol

函数原型：

char *_itoa( int value, char *string, int radix );  //ANSI
wchar_t * _itow( int value, wchar_t *string, int radix );//UNICODE

_itot 只是一个宏，根据系统定义的字符集来去_itoa或者_itow， 对应的安全函数为_itot_s
说明:把int 转化为字符串,value为被转化的值,string为转化的目的字符串, radix为基数必须在2到36之间.
所需头文件 #include <stdlib.h>
举例说明:这里用它们的安全函数: _itoa_s    _itow_s
char szYearA[5] = {0};
WCHAR szYearW[5] = {0};
_itoa_s(100, szYearA, 10);
_itow_s(100, szYearW, 10);


atoi     atof     atol

Convert strings to double (atof), integer (atoi, _atoi64), or long (atol).

double atof( const char *string );
int atoi( const char *string );
_int64 _atoi64( const char *string );
long atol( const char *string );
举例：
	double d1 = atof("sa34");  //d1 = 0.00000000000000000
	double d2 = atof("34gdf"); //d2 = 34.000000000000000
	double d3 = atof("-0343"); //d3 = -343.00000000000000
	double d4 = atof("008");   //d4 = 8.0000000000000000
	int i1 = atoi("df");       //i1 = 0
	int i2 = atoi("54.34");    //i2 = 54
	int i3 = atoi("-54");      //i3 = -54
	int i4 = atoi("09");       //i4 = 9