atof函数
原型：double atof const char *string );
ASCII to float
作用：将字符串转为double类型
对于以上函数，若字符串无法转化为合法的数值类型，函数将返回0 。
使用范例（来甜甜的保温杯）：
1#include <stdlib.h>
2#include <stdio.h>
3
4void main void )
5{
6 char *s; double x; int i; long l;
7
8 printf ” testing atoi,atof,atol function :\n” ) ;
9 s = ” -2309.12E-15″; /* Test of atof */
10 x = atof s );
11 printf “atof test: ASCII string: %s\tfloat: %e\n”, s, x );
12
13 s = “7.8912654773d210”; /* Test of atof */
14 x = atof s );
15 printf “atof test: ASCII string: %s\tfloat: %e\n”, s, x );
16
17 s = ” -9885 pigs”; /* Test of atoi */
18 i = atoi s );
19 printf “atoi test: ASCII string: %s\t\tinteger: %d\n”, s, i );
20
21 s = “98854 dollars”; /* Test of atol */
22 l = atol s );
23 printf “atol test: ASCII string: %s\t\tlong: %ld\n”, s, l );
24}
25
输出：
atof test: ASCII string: -2309.12E-15 float: -2.309120e-012
atof test: ASCII string: 7.8912654773d210 float: 7.891265e+210
atoi test: ASCII string: -9885 pigs integer: -9885
atol test: ASCII string: 98854 dollars long: 98854</pkfdgz