[C++知识库]笨办法学C语言-习题七-变量和类型

#include<stdio.h>

int main (int arg,char *argv[])
{
    int distance = 100;
    float power  = 2.345f;
    double super_power = 56789.4532;
    char initial = 'A';
    char first_name[] = "zed";
    char last_name[] = "shaw";

    printf("you are %d miles away.\n",distance);
    printf("you have %f levels of power.\n",power);
    printf("you have %f awesome super power.\n",super_power);
    printf("I have an initial %c.\n",initial);
    printf("I have a first name %s.\n",first_name);
    printf("I have a last name %s.\n",last_name);

    int bug = 100;
    double bug_rate = 1.2;

    printf("YOu have %d,%f.\n",bug,bug_rate);

    long universe_of_detects = 1L * 1024L * 1024L * 1024L;
    printf("universe_of_detects = %ld",universe_of_detects);



    return 0;
    
}

重点问题（1）int和long最大多少
可以发现原数据中的定义long变为int还是满足数据长度

long再乘以10倍发现已经报错
warning: integer overflow in expression of type ‘long int’ results in ‘-2147483648’ [-Woverflow]
long universe_of_detects = 1L * 10240L * 1024L * 1024L;

（2）%c和%s使用问题

字符用字符串打印会报错

字符串用字符打印程序不报错，但是打印内容报错。

char initial = ‘A’; //这个是定义一个字符，注意‘’单引号。
char initial =“A”; //这个是定义一个字符串，注意”“双引号。

字符串就是”字符数组“，利用数组访问的形式可以访问字符串里的字符。