---------请问怎么转换char到float---------
请问怎么才可以把char a[]={ "100 "}转换成float型的 100

[解决办法]
返回的是double类型，可能返回的不是100，精度上需要你自己注意一下。
[解决办法]
#include <stdlib.h>
#include <stdio.h>

void main( void )
{
char *s; double x; int i; long l;

s = " -2309.12E-15 "; /* Test of atof */
x = atof( s );
printf( "atof test: ASCII string: %s\tfloat: %e\n ", s, x );

s = "7.8912654773d210 "; /* Test of atof */
x = atof( s );
printf( "atof test: ASCII string: %s\tfloat: %e\n ", s, x );

s = " -9885 pigs "; /* Test of atoi */
i = atoi( s );
printf( "atoi test: ASCII string: %s\t\tinteger: %d\n ", s, i );

s = "98854 dollars "; /* Test of atol */
l = atol( s );
printf( "atol test: ASCII string: %s\t\tlong: %ld\n ", s, l );
}
Output

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