4. 字符串转换数值atoi atol atof

#include <stdlib.h>
int atoi(const char *nptr);
long atol(const char *nptr);

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

void test01()
{
        printf("%d\n", atoi("123")); //123
        printf("%d\n", atoi("123abc"));//123
        printf("%d\n", atoi("abc123"));//提取失败
        printf("%f\n", atof("3.14"));//3.14
}

int main()
{
        test01();
        return 0;
}