Why if condition is not stopping on single statement?

Question

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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?

C++

#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();
}

Posted 21-Mar-13 11:35am

vishal2592

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Comments

vishal2592 22-Mar-13 1:05am

Why scanf("%c",&op) is not working anywhere in program except first place?
actually i want to used "enter operator in second number during program execution but it is not working in second place why?

vishal2592 22-Mar-13 1:16am

I assign the value of char in scanf("%c",&ope); section?

[no name] 21-Mar-13 17:48pm

You are doing assignment operations in your if statements not comparison operations.

Matt T Heffron 21-Mar-13 18:38pm

Both Maciej Los and ThePhantomUpvoter's comments are correct.

Also, you are attempting to compare a char with a string.

An easy way to prevent falling into the "assignment in the if statement condition" is to put the constant to the left of the equality comparison:

if ('+' == op) ...

If you accidentally used the single "=" assignment operator, the compilation will fail.

vishal2592 22-Mar-13 1:05am

Why scanf("%c",&op) is not working anywhere in program except first place?
actually i want to used "enter operator in second number during program execution but it is not working in second place why?

2 solutions

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Matt T Heffron · Accepted Answer · 2013-03-22T10:36:00

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

C++

#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();
}

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.

Maciej Los · Accepted Answer · 2013-03-21T12:08:00

Solution 1

For the first look, you forgot about { and }

C#

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

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

More about: if[^].

Posted 21-Mar-13 12:08pm

Maciej Los

Comments

Sergey Alexandrovich Kryukov 21-Mar-13 20:15pm

5ed.
—SA

Maciej Los 22-Mar-13 2:34am

Thank you, Sergey ;)