C语言实例10：if-else语句

/******************
原题：有一分段函数，y=f(x).当x小于6时，y= x - 12;
                         当x大于6且小于15时，y = 3x - 1;
                         当x大于等于15时，y = 5x + 9;
*******************/
#include <stdio.h>

int main(int argc, char *argv[])
{
    int x, y;
    printf("请输入自变量： ");
    scanf("%d",&x);

    if(x < 6)
    {
        y = x -12;
        printf("x = %d, y = %d\n",x ,y);
    }
    else if(x < 15)
    {
        y = 3*x - 1;
        printf("x = %d, y = %d\n",x ,y);
    }
    else
    {
        y = 5*x +9;
        printf("x = %d, y = %d\n",x ,y);
    }

    while(1);

    return 0;
}