Execution Problem

[leesandy44]

can anyone help me to write a c program to swap two numbers? i wrote the following program. at the compilation its not making any errors, but at the execution its not giving the correct output. actually its not swapping the numbers. Please help me to find the error.

Code: Select all

#include<conio.h>
void main()
{
   int a; int b; int temp;
   a=0, b=0;
   clrscr();
   printf("Input two numbers\n');
   scanf("%d%d",&a,&b);
   temp=a;
   b=a;
   b=temp;
   printf("%d%d",a,b,);
   getch();
}

[Neo]

The corrected program can be found below.

Code: Select all

    #include<conio.h>
    void main()
    {
       int a; int b; int temp;
       a=0, b=0;
       clrscr();
       printf("Input two numbers\n');
       scanf("%d%d",&a,&b);
       temp=a;
       a=b;
       b=temp;
       printf("%d%d",a,b,);
       getch();
    }

Note a=b;, you used b=a so it is a simple bug.
When you define variables in a single line you could use as below (you may also set initial values).

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int a = 0, b = 0, temp;

However the swap can be written more meaningfully using pointers as below.

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    #include <stdio.h>

    void swap(int *a, int *b){

       int temp;

       temp = *a;
       *a = *b;
       *b = temp;
    }

    void main()
    {
       int a = 0, b = 0, temp;
       clrscr();
       printf("Input two numbers\n');
       scanf("%d%d", &a, &b);

       swap( &a, &b);

       printf("%d%d",a,b,);
       getch();
    }

[leesandy44]

that means there's a special keyword for swapping???

[Neo]

No. Not a keyword.
We have written a function void swap(int *a, int *b) for this.

[leesandy44]

okay. thank you Neo. still i haven't learn much functions. thank you so much for the help.

[Neo]

You are always welcome. This is the purpose of ROBOT.LK.
If you have any problem, do not hesitate to submit.

[leesandy44]

Neo I wrote the following program. But it has a compilation error. It says "Misplaced else". could you please help me to correct this???

Code: Select all

#include<conio.h>
void main()
{
    int m;
    m=0;
    clrscr();
    printf("input module mark");
    scanf("%d"\n",&m);
    if(m>=50);
    {
       printf("you are pass");
    }
    else
    {
        printf("you are fail");
     }
    getch();
}

[Neo]

Remove the semicolon in red colour. This will tell the compiler that if command ends with semicolon so the else is not valid.

#include<conio.h>
void main()
{
int m;
m=0;
clrscr();
printf("input module mark");
scanf("%d"\n",&m);
if(m>=50);
{
printf("you are pass");
}
else
{
printf("you are fail");
}
getch();
}

[leesandy44]

thank you Neo. Now its working.

[leesandy44]

please help me to find the error of the following program...

Code: Select all

#include<conio.h>
void main()
{
	int i,j;
	for(j=1;j<10;j++);
	{
		if(j%3==0)
		{
			continue
		}
		printf("j=%d",j);
	}
	getch();
}

i wanna know more about continue keyword. please send me some sites or some details..