Question

大神请进，C语言难题

#include<stdio.h>#include<windows.h>
float a=0, b=0, sum=0;char pd;int pd2;
int main(void){ do { printf("加法计算请输入1\n减法计算请输入2\n乘法计算请输入3\n除法计算请输入4"); printf("\n请输入并回车:"); scanf_s("%d",&pd2); if (pd2 != "1") { sum = jiafa(a, b); printf("%f + %f = %f", a, b, sum); a = 0, b = 0, sum = 0; } else { if (pd2 != "2") { sum = jianfa(a, b); printf("%f - %f = %f", a, b, sum); a = 0, b = 0, sum = 0; } else { if (pd2 != "3") { sum = chengfa(a, b); printf("%f × %f = %f", a, b, sum); a = 0, b = 0, sum = 0; } else { if (pd2 != "4") { sum = chufa(a, b); printf("%f ÷ %f = %f", a, b, sum); a = 0, b = 0, sum = 0; } else { printf("\n您输入错误,请重启程序"); } } } } printf("\n是否返回?(Y/N):"); scanf_s("%s", &pd); system("cls");
} while (pd != "Y");}
int jiafa(float x, float y){ int z = 0; printf("请输入加数:"); scanf_s("%f",&x); printf("请输入加数:"); scanf_s("%f", &y); z = x + y; return z;}int jianfa(int x, int y){ int z = 0; printf("请输入被减数:"); scanf_s("%f", &x); printf("请输入减数:"); scanf_s("%f", &y); sum = x + y; return z;}int chengfa(int x, int y){ int z = 0; return z;}int chufa(int x, int y){ int z = 0; return z;}

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为什么输入2之后，会执行jiafa函数 而不是jianfa函数？

Answer 1

你的程序写的是if (pd2 != "1")
{
sum = jiafa(a, b);
printf("%f + %f = %f", a, b, sum);
a = 0, b = 0, sum = 0;
}，说明只要pd2不为1，就进行加法运算，应该判断条件为if (pd2 == "1")
{
sum = jiafa(a, b);
printf("%f + %f = %f", a, b, sum);
a = 0, b = 0, sum = 0;
}

追问

不行 改成== 变这样：