Thread: Repetition structure not working?!?

For some reason my repetition structure is not working correctly. I do not get any compiler errors, but the calculation only happens the first time I choose one of my options. After the result is displayed the first time, the options repeat, I select an option and enter the data, then get an error instead of calculation.

I have used repetition before, and have not had this problem until now.
Can anyone help me resolve this issue?

Code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define maxR 2
#define maxC 2

void doEval();
int doAdd();
int doSub();
char doQuit(char);

main()
{
      doEval();
      return 0;
}

void doEval()
{
      char userInput[2048];
      int row, col;
      int arrayA[maxR][maxC];
      int arrayB[maxR][maxC];
      int arrayZ[maxR][maxC];
      char optionA;

      printf("Enter one of the following options:\n\
                Q - Quit the program\n\
                A - Add 2 matrices of size   5 x 5\n\
                S - Subtract 2 matrices of size   5 x 5\n\
                     Enter option: ");

        fgets(userInput,2048,stdin);
        if((strstr(userInput,"Q") != NULL) || 
                        (strstr(userInput,"q") != NULL)) {
                             optionA = doQuit(optionA);
        } else if ((strstr(userInput,"A") != NULL) || 
                        (strstr(userInput,"a") != NULL)) {
                             arrayZ[maxR][maxC] = doAdd(arrayZ[maxR][maxC]);
        } else if ((strstr(userInput,"S") != NULL) || 
                        (strstr(userInput,"s") != NULL)) {
                             arrayZ[maxR][maxC] = doSub(arrayZ[maxR][maxC]);
        } else {
               printf("Not Valid, Pleas Try Again");
               }
    doEval();
    return;

}

int doAdd(int arrayZ[maxR][maxC])
{   
      int row, col;
      int arrayA[maxR][maxC];
      int arrayB[maxR][maxC];
         
        printf("Enter Matrices\n");
        printf("Matrix 1: \n");
          for (row = 0; row < maxR; row++) {
                for (col = 0; col < maxC; col++) {
                        scanf("%d", &arrayA[row][col]);
                }
        }
        printf("Matrix 2: \n");
          for (row = 0; row < maxR; row++) {
                for (col = 0; col < maxC; col++) {
                        scanf("%d", &arrayB[row][col]);
                }
        }
        printf("\n");
        printf("Sum of Matrices:\n");
          for (row = 0; row < maxR; row++) {
                for (col = 0; col < maxC; col++) {
                   arrayZ[row][col] = arrayA[row][col] + arrayB[row][col];
                        printf ("% 5d ", arrayZ[row][col]);
                }
                printf ("\n\n");
        }
   scanf("%*c");
   return arrayZ[row][col];
}


int doSub(int arrayZ[maxR][maxC])
{   
      int row, col;
      int arrayA[maxR][maxC];
      int arrayB[maxR][maxC];
         
        printf("Enter Matrices\n");
        printf("Matrix 1: \n");
          for (row = 0; row < maxR; row++) {
                for (col = 0; col < maxC; col++) {
                        scanf("%d", &arrayA[row][col]);
                }
        }
        printf("Matrix 2: \n");
          for (row = 0; row < maxR; row++) {
                for (col = 0; col < maxC; col++) {
                        scanf("%d", &arrayB[row][col]);
                }
        }
        printf("\n");
        printf("Difference of Matrices:\n");
          for (row = 0; row < maxR; row++) {
                for (col = 0; col < maxC; col++) {
                   arrayZ[row][col] = arrayA[row][col] - arrayB[row][col];
                        printf ("% 5d ", arrayZ[row][col]);
                }
                printf ("\n\n");
        }
   scanf("%*c");
   return arrayZ[row][col];
}


char doQuit(char optionA)
{
     exit(0);
}

As cool as recursion is, maybe you're running out of stack memory. Start using loops for this kind of repetition and you will avoid this problem.

Thank you for the input. I am actually doing this for a class assignment, and we are practicing with functions, so I must use functions to complete all of my tasks. We also assume that the user enters everything exactly how we want them to. I did place everything in a do while loop, and got rid of the void doEval function, but I still get an error with the second time I try to enter my data.

Are there any other things I may be overlooking?

Using functions to complete all of your tasks does not mean "don't use flow control statements like while". If your instructor lowers your grade, just ignore it. What you're learning to do in this particular area is goofy.

I added a do while loop, and got rid of the doEval, but my repetition is still giving the same issues. The program runs fine first time I make a selection and calculate the results, but after my printf options display again and I make my selection it does not calculate.

Code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define maxR 2
#define maxC 2

int doAdd();
int doSub();
char doQuit(char);

main()
{
      doEval();
      return 0;

      char userInput[2048];
      int row, col;
      int arrayA[maxR][maxC];
      int arrayB[maxR][maxC];
      int arrayZ[maxR][maxC];
      char optionA;
do {
      printf("Enter one of the following options:\n\
                Q - Quit the program\n\
                A - Add 2 matrices of size   5 x 5\n\
                S - Subtract 2 matrices of size   5 x 5\n\
                     Enter option: ");

        fgets(userInput,2048,stdin);
        if((strstr(userInput,"Q") != NULL) || 
                        (strstr(userInput,"q") != NULL)) {
                             optionA = doQuit(optionA);
        } else if ((strstr(userInput,"A") != NULL) || 
                        (strstr(userInput,"a") != NULL)) {
                             arrayZ[maxR][maxC] = doAdd(arrayZ[maxR][maxC]);
        } else if ((strstr(userInput,"S") != NULL) || 
                        (strstr(userInput,"s") != NULL)) {
                             arrayZ[maxR][maxC] = doSub(arrayZ[maxR][maxC]);
        } else {
               printf("Not Valid, Pleas Try Again");
               }
    }while(0 == 0);
    return;

}

int doAdd(int arrayZ[maxR][maxC])
{   
      int row, col;
      int arrayA[maxR][maxC];
      int arrayB[maxR][maxC];
         
        printf("Enter Matrices\n");
        printf("Matrix 1: \n");
          for (row = 0; row < maxR; row++) {
                for (col = 0; col < maxC; col++) {
                        scanf("%d", &arrayA[row][col]);
                }
        }
        printf("Matrix 2: \n");
          for (row = 0; row < maxR; row++) {
                for (col = 0; col < maxC; col++) {
                        scanf("%d", &arrayB[row][col]);
                }
        }
        printf("\n");
        printf("Sum of Matrices:\n");
          for (row = 0; row < maxR; row++) {
                for (col = 0; col < maxC; col++) {
                   arrayZ[row][col] = arrayA[row][col] + arrayB[row][col];
                        printf ("% 5d ", arrayZ[row][col]);
                }
                printf ("\n\n");
        }
   scanf("%*c");
   return arrayZ[row][col];
}


int doSub(int arrayZ[maxR][maxC])
{   
      int row, col;
      int arrayA[maxR][maxC];
      int arrayB[maxR][maxC];
         
        printf("Enter Matrices\n");
        printf("Matrix 1: \n");
          for (row = 0; row < maxR; row++) {
                for (col = 0; col < maxC; col++) {
                        scanf("%d", &arrayA[row][col]);
                }
        }
        printf("Matrix 2: \n");
          for (row = 0; row < maxR; row++) {
                for (col = 0; col < maxC; col++) {
                        scanf("%d", &arrayB[row][col]);
                }
        }
        printf("\n");
        printf("Difference of Matrices:\n");
          for (row = 0; row < maxR; row++) {
                for (col = 0; col < maxC; col++) {
                   arrayZ[row][col] = arrayA[row][col] - arrayB[row][col];
                        printf ("% 5d ", arrayZ[row][col]);
                }
                printf ("\n\n");
        }
   scanf("%*c");
   return arrayZ[row][col];
}


char doQuit(char optionA)
{
     exit(0);
}

i am currently inputting '1 2 3 4' for both matrices, and using the 'A' option

I think it might be the dev-C++ compiler. I have heard that I might need to use 'int *' rather than 'int'. How do I do that?