为什么条件没有在单一陈述上停止？ [英] Why if condition is not stopping on single statement?

问题描述

我收到错误，该程序将执行所有操作，即Add，Sub等，但我只想执行单个操作。

我怎么做？

和

为什么scanf（％c，& op）在程序中的任何地方都没有工作，除了第一名？

I got error that this program will execute for all operation i.e Add,Sub etc but i want to execute it only for single operation.
How i can do it?
and
Why scanf("%c",&op) is not working anywhere in program except first place?

#include<stdio.h>
int add(int x,int y)
{
    int z;
    z=x+y;
    return z;
}
int multi(int x,int y)
{
    int z;
    z=x*y;
    return z;
}
int divi(int x,int y)
{

    int z;
    z=x/y;
    return z;
}

int sub(int x,int y)
{

    int z;
    z=x-y;
    return z;
}
main()
{
    int z;
    int firstv,secv;
    char op;
    printf("Please enter operator\n");
    scanf("%c",&op);
    printf("Please enter first value to calculation\n");
    scanf("%d",&firstv);
    printf("Please enetr second number\n");
    scanf("%d",&secv);
        if (op="+")
        z= add(firstv,secv);
        printf("The addtion of %d and %d is %d\n",firstv,secv,z);
        if (op="-")
        z=sub(firstv,secv);
        printf("The substration of %d and %d is %d\n",firstv,secv,z);

        if (op="*")
        z= multi(firstv,secv);
        printf("the multiplication of %d and %d is %d\n",firstv,secv,z);

        if(op="/")
        z=divi(firstv,secv);
        printf("The division of %d and %d is %d",firstv,secv,z);

        getch();
}

推荐答案

我不知道你的scanf问题。

使用Visual Studio 2010，我试过这个并且它有效：

I don''t know about your scanf issue.
With Visual Studio 2010, I tried this and it worked:

#include<conio.h>
int main()
{
    int z;
    int firstv,secv;
    char op;
    printf("Please enter operator\n");
    scanf("%c",&op);
    printf("Please enter first value to calculation\n");
    scanf("%d",&firstv);
    printf("Please enetr second number\n");
    scanf("%d",&secv);
    if (op=='+')
    {
        z= add(firstv,secv);
        printf("The addtion of %d and %d is %d\n",firstv,secv,z);
    }
    if (op=='-')
    {
        z=sub(firstv,secv);
        printf("The substration of %d and %d is %d\n",firstv,secv,z);
    }
    if (op=='*')
    {
        z= multi(firstv,secv);
        printf("the multiplication of %d and %d is %d\n",firstv,secv,z);
    }
    if(op=='/')
    {
        z=divi(firstv,secv);
        printf("The division of %d and %d is %d",firstv,secv,z);
}
    _getch();
}

我修复了赋值/比较问题并将比较改为char而不是字符串（编译器在比较中不会用字符串编译它） 。

试试看看会发生什么。

I fixed the assignment/comparison problem and changed the comparisons to be char not string (the compiler wouldn''t compile it with strings in comparisons).
Try this and see what happens.

第一眼看，你忘记了 {和}

For the first look, you forgot about { and }

if (condition statement)
{
//code block to execute if condition is true
//line 2
}
else
{
//code block to execute if condition is false
//line 2
}

你不需要 {和} 如果执行sin gle line



更多关于：如果 [ ^ ]。

You don''t need { and } if you execute single line

More about: if[^].

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