Unknown problem

This is a discussion on Unknown problem within the C Programming forums, part of the General Programming Boards category; Okay, here's the code: Code: #include <stdio.h> #include <string.h> void add(char **data, int rows); void del(char **data, int rows); void ...

  1. #1
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    Plymouth, U.K.
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    Unknown problem

    Okay, here's the code:
    Code:
    #include <stdio.h>
    #include <string.h>
    
    void add(char **data, int rows);
    void del(char **data, int rows);
    void display(char **data, int rows);
    void save(char **data, int rows, FILE * fp);
    void menu();
    
    int main()
    {
        int x;
        int q;
        int quit;
        char **data;
        FILE * fp = fopen("list.dat", "r+");
        if(fp == NULL)
        {
              fp = fopen("list.dat", "w+");
        }
        for(x=0;fgets(data[x], 1000, fp) != NULL;x++);
        {
                              fgets(data[x], 1000, fp);
        }
        while(quit != 1){
        menu();
        scanf("%d", q);
        switch(q)
        {
                    case 1:{
                         add(data, x);
                         save(data, x, fp);
                         }
                    case 2:{
                         del(data, x);
                         save(data, x, fp);
                         }
                    case 3:{
                         display(data, x);
                         }
                    case 4:{
                         quit = 1;
                         }
        }
    }
    fclose(fp);
    return(0);
    }                     
          
    void add(char **data, int rows){
         char *add;
         printf("Please enter string to be added to the data file: ");
         scanf("%s", *add);
         strcat(add, "\n");
         strcpy(data[rows+1], add);
         }
         
    void del(char **data, int rows){
         int del;
         display(data, rows);
         printf("Please enter the number of the entry to be deleted: ");
         scanf("%d", del);
         data[del]= "";
         }
    
    void display(char **data, int rows){
         int i;
         for(i=0;i<=rows;i++){
         printf("[%d]\t%s\n",i,data[i]);
         }
         }
         
    void save(char **data, int rows, FILE * fp){
         int i;
         for(i=0;i<=rows; i++){
                          strcat(data[i], "\n");
                          fputs(data[i], fp);
                          }
         }
    
    void menu(){
         printf("Welcome to the menu.\n");
         printf("1) Add data to the file.\n");
         printf("2) Remove data from the file.\n");
         printf("3) Display contents of the file.\n");
         printf("4) Exit the program.\n");
         printf("Please insert the corresponding number for the function you wish to perform: ");
         }
    On compile it has no errors - but when I run it, it crashes before it displays the menu (menu(). I'm not sure why, do any of you have any ideas? Also, feel free to tell me where my code is inefficient

  2. #2
    Registered User Tonto's Avatar
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    Code:
        for(x=0;fgets(data[x], 1000, fp) != NULL;x++);
        {
                              fgets(data[x], 1000, fp);
        }
    Can you see it now? Also

    Code:
        FILE * fp = fopen("list.dat", "r+");
        if(fp == NULL)
        {
              fp = fopen("list.dat", "w+");
        }
    That's kind of silly. Edit: And finally, scanf accepts a pointer

    Code:
    scanf("%d", q);
    scanf("%d", &q);

  3. #3
    Registered User
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    Plymouth, U.K.
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    Quote Originally Posted by Tonto
    Code:
        for(x=0;fgets(data[x], 1000, fp) != NULL;x++);
        {
                              fgets(data[x], 1000, fp);
        }
    Can you see it now? Also

    Code:
        FILE * fp = fopen("list.dat", "r+");
        if(fp == NULL)
        {
              fp = fopen("list.dat", "w+");
        }
    That's kind of silly. Edit: And finally, scanf accepts a pointer

    Code:
    scanf("%d", q);
    scanf("%d", &q);
    I was told to do the for loop like that by a friend after my code didn't work the first time. What's wrong with the fopen part? And finally, oops at forgetting the &

  4. #4
    Registered User ortegac's Avatar
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    Talking See if this help

    Code:
    --------------------Configuration: ass5pract - Win32 Debug--------------------
    Compiling...
    ass5pract.c
    C:\Documents and Settings\Famili@\My Documents\aaron\CM22\ass5pract.c(21) : warning C4700: local variable 'data' used without having been initialized
    C:\Documents and Settings\Famili@\My Documents\aaron\CM22\ass5pract.c(27) : warning C4700: local variable 'q' used without having been initialized
    C:\Documents and Settings\Famili@\My Documents\aaron\CM22\ass5pract.c(53) : warning C4700: local variable 'add' used without having been initialized
    C:\Documents and Settings\Famili@\My Documents\aaron\CM22\ass5pract.c(62) : warning C4700: local variable 'del' used without having been initialized
    
    ass5pract.obj - 0 error(s), 4 warning(s)
    You get 4 warnings they are not intialized, dont you think that is messing it up?

    Also try to only one with one function at a time. Examples use only the funtion to display, try too break your program in smaller parts. To see where the error is?
    Then if you see the display funtions works, add another one an so on.

    Caleb

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