switch case syntax

[sedaw]

if i want right after performed case (number): {.......}
go back to the menu .

why the prog goes on to case 2 after perform case 1 ?

#include <stdio.h>
#define size 50 //max
void main()
{
    int sel, cols, rows, i, j, arr[size][size]={0} ;
    printf("enter rows and cols [1..50] ==>");
    scanf("%d",&cols);
    scanf("%d",&rows);
    printf("1. display the matrix\n"
           "2. input values to matrix\n"
           "3. transpose matrix\n"
           "4. i-th power\n"
           "5. sort the matrix by rows sum\n"
           "6. find sub matrices\n"
           "7. long addition\n"
           "0. quit\n");
    scanf("%d",&sel);
    switch(sel)
    {
    case 1:
        for(i=0; i<cols; i++)
        {
            printf("\n");
            for(j=0; j<rows; j++)
                printf("%d",arr[i][j]);
        }
    case 2:
        printf("enter data for %dx%d ==>",rows,cols);
 
    }
    getchar();
 
}
 
 
 

[weaknessforcats]

That is a feature of the switch statement.

If you want just one case to execute, you need a break statement at the end of the case:

case 1:
            //logic here
            break;

The fall-through features lets you use the same logic for several cases:

case Jan:
case Mar:
case May:
case Jul:
case Aug:
case Oct:
case Dec:
        NumberOfDays = 31;
        break;

[sedaw]

ok... but after the break i want to go back to main menu
and now let the user select another case (another number)
what bout this:

#include <stdio.h>
#define size 50 //max
void main()
{
    int sel=-1, cols, rows, i, j, arr[size][size]={0} ;
    printf("enter rows and cols [1..50] ==>");
    scanf("%d",&cols);
    scanf("%d",&rows);
    switch(sel)
    {
    case 1:
        for(i=0; i<cols; i++)
            for(j=0; j<rows; j++)
                printf("%d",arr[i][j]);
            break;
    default:
    printf("1. display the matrix\n"
           "2. input values to matrix\n"
           "3. transpose matrix\n"
           "4. i-th power\n"
           "5. sort the matrix by rows sum\n"
           "6. find sub matrices\n"
           "7. long addition\n"
           "0. quit\n");
    scanf("%d",&sel);
    }
    getchar();
}
 

still not workin`

TNX .............

[weaknessforcats]

That's because your scanf is part of the default case.

Remember, the switch is just a series if if-else logic blocks. As soon as you break, you have left the switch statement.

To go back and scan another choice you need a loop with the switch inside the loop:

while (1)
{
     scanf(choice);
     switch (choice)
     {
 
     }
}

In this setup you stay in the loop forever. When you scanf to quit, you need to leave the function containing the loop. Like this:

case quit:
          //do the cleanup here
          return;   

That will return from the function containing the while loop. If the while loop is in your main(), this is the return from main().

[sedaw]

thank you very much!
you helped me alot (-: