Question

大神请进，C语言问题

#include<stdio.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("您输入错误,请重启程序"); } } } } printf("是否返回?(Y/N):"); scanf_s("%s", pd);
} 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; return z;}int chengfa(int x, int y){ int z = 0; return z;}int chufa(int x, int y){ int z = 0; return z;}
//------------------------------------------------------------------------------------------------------------------------

请问 为什么输入1后（2、3、4不计）便无响应？

Answer 1

1. scanf请取地址

2. 字符读取用%c

3. 字符比较，字面值用'Y'（单引号）

4. 函数声明放在调用前（main函数前，你可以放在mian函数前实现）
   

Answer 2

  scanf_s("%d", & pd2);//这里少了&符号 后面的其他scanf_s输入也要加上
  
  if (pd2 == 1) //整数常量不能再引号，有引号表示字符串，后面的其比较也要改一下
  
  scanf("%c", &pd ); //读字符用%c 
  } while (pd == 'Y'); //字符常量要用单引号引起来！

Answer 3

main函数里的 scanf_s("%d",pd2);
改为：scanf_s("%d",&pd2);试试
希望对你有帮助

Answer 4

printf("\n请输入并回车:");
scanf_s("%d",pd2);

=>
差一个&
scanf_s("%d",&pd2);