Simple search program

This is a discussion on Simple search program within the C Programming forums, part of the General Programming Boards category; Hi Guys, I have a tutorial question that ask that I make a program to hold students names and grades. ...

  1. #1
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    Simple search program

    Hi Guys,

    I have a tutorial question that ask that I make a program to hold students names and grades.

    I must be able to search by name or ID number.

    I have the programe running except the search by name, if there is more than 1 record with the same name i get a general protection fault adn the program crashes, if there is just 1 name in the records the search works fine.

    I wonder of someone could look at my function "search_for_name()" and guide me in the right direction.

    Many thanks in advance
    C


    Code:
    #include<stdio.h>
    #include<conio.h>
    #include<string.h>
    
    /*xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx*/
    /*struct for a student */
    
    typedef struct
    {
    	char name[20];
    	int grade1;
    	int grade2;
    	int grade3;
    	int grade4;
    	int id;
    }  names;
    
    /*xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx*/
    
    #define MAX 999
    
    names names_database[20];
    int index=0;
    int id=100;
    /*xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx*/
    
    /* Functions used in this program */
    void menu_controller(void);
    void draw_menu(void);
    int get_menu_option(void);
    void process_menu_option(int option);
    void add_new_name(void);
    void search_for_name(void);
    void search_for_id(void);
    
    /*xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx*/
    
    /*The main program*/
    
    void main(void)
    {
         menu_controller();
    }
    
    /*xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx*/
    
    /* These are the specifications for the functions called*/
    
    void menu_controller()
    {
    /*This function is the main controlling routine for our menu*/
    int menu_choice=0;
    
    /*The controlling loop for the whole programe*/
    while(menu_choice !=9)
    {
    /*step 1 draw menu*/
    draw_menu();
    
    /*Step2 - Prompt for a user responce*/
    menu_choice=get_menu_option();
    
    /*Step3 - Action the users choice*/
    process_menu_option(menu_choice);
    }
    }
    
    /*xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx*/
    
    void draw_menu(void)
    {
    /*This function simply draws the main menu - nothing else*/
    clrscr();
    /* Display the menu options*/
    printf("\n\n\t\t      Student Search program\n\n");
    printf("\t\t\t 1. Add new name and 4 exam percentages\n");
    printf("\t\t\t 2. Search by name\n");
    printf("\t\t\t 3. Search by ID number\n");
    printf("\t\t\t 9. Quit\n");
    }
    /*xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx*/
    
    int get_menu_option(void)
    {
    /*This function returns the menu option selected by the user*/
    int option;
    
    printf("\n\n\n\t\t    Please enter your option:  ");
    scanf("%d", &option);
    fflush(stdin);
    return option;
    }
    
    /*xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx*/
    
    void process_menu_option(int option)
    {
    /*An intiger to hold the value returned by getchar() */
    int key;
    
    /*This function eveluates each option and calls the appropriate function*/
    
    switch(option)
    {
    	case 1 : add_new_name();
    								break;
    
    	case 2 : search_for_name();
    								break;
    
    	case 3 : search_for_id();
    								break;
    
    	case 9 : printf("\n\nThank you, the program will now exit....\n");
    								break;
    
    	default : printf("\n\nSorry that is not a valid option - press enter to continue");
    							  key = getchar();
    								break;
    }    /* End switch*/
    }    /* End process_menu_option() */
    
    /*xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx*/
    /*These are the functions for our menu options, but they dont do much... */
    
    void add_new_name(void)
    {
    
    clrscr();
    
    /* Add the name and DOB to the database*/
    
    printf("\n\n\t\t   Enter new name and Grades\n\n");
    printf("Enter new name: ");
    gets(names_database[index].name);
    fflush(stdin);
    
    printf("Please enter 4 grade marks in as a percentage value:\n\n");
    scanf("%d%d%d%d",&names_database[index].grade1, &names_database[index].grade2,
    &names_database[index].grade3,&names_database[index].grade4);
    fflush(stdin);
    names_database[index].id =id;
    /* Increment the student array & id position*/
    index++;
    id++;
    }
    
    /*xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx*/
    void search_for_name(void)
    {
    
    int found = 0;
    int result;
    nt loop=0;
    int key;
    int average;
    char name[20];
    clrscr();
    
    printf("Please enter the name to search for: ");
    gets(name);
    fflush(stdin);
    
    while(found==0 && loop < MAX)
    {
    result = strcmp(names_database[loop].name,name);
    
    if(result ==0)
    {
    average = (names_database[loop].grade1 + names_database[loop].grade2 +
    names_database[loop].grade3 + names_database[loop].grade4) / 4 ;
    printf("The average grade for %s is %d the ID number is %d\n",names_database[loop].name,average,names_database[loop].id);
    found=1;
    }
     loop++;
    
    }
    if(loop == MAX)
    {
    printf("NOT FOUND\n");
    		 }
    
     key = getchar();
    
    
    
    }
    /*xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx*/
    void search_for_id(void)
    {
    int found = 0;
    int loop=0;
    int average;
    int key;
    int getid;
    clrscr();
    
    printf("Please enter the ID Number to search for between 100 & 999: ");
    scanf("%d",&getid);
    fflush(stdin);
    
    
    if ( getid == names_database[loop].id)
    
    				{
    average = (names_database[loop].grade1 + names_database[loop].grade2 +names_database[loop].grade3 + names_database[loop].grade4) / 4 ;
    
    printf("The average grade for %s is %d the ID number is %d\n",names_database[loop].name,average,names_database[loop].id);
    found=1;
    
    				}
    if ( getid != names_database[loop].id)
    {
    	printf("NOT FOUND\n");
    
    }
    loop++;
    key = getchar();
    		
           
    
    
    
    }

  2. #2
    Registered User
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    >#define MAX 999
    >names names_database[20];
    >.
    >.
    >while(found==0 && loop < MAX)

    You've only got an array of 20 names, but your loop runs to 999, way off the end of the array.

  3. #3
    Registered User
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    Thank you

    Thanks very much swoopy that seems to have done the trick

  4. #4
    Banned master5001's Avatar
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    Welcome to the world of buffer overflow. Stop learning how to prevent it colinuk, it may hinder your ability to ever work at Microsoft.

  5. #5
    Widdle Coding Peon Aerie's Avatar
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    Laff.
    I live in a giant bucket.

  6. #6
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    Good one Master5001.

    >fflush(stdin);

    Colinuk, glad that worked. One other problem. fflush(stdin) is wrong. See:
    FAQ > Explanations of > Why fflush(stdin) is wrong

    and FAQ > How do I > Flush the input buffer

  7. #7
    Banned master5001's Avatar
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    About buffer overflows again, you need to be careful since sometimes they come up from simple mistakes such as typoes.

    Example:
    Code:
    int array[200], i;
    
    for(i = 0; i < 2000; i++) {
      array[i] = getchar();
    }
    In the above code, oops I typed 2000 instead of 200. This is another reason why I promote not using "magic numbers." Its harder to get away with simple typing erros when typing something like:

    Example:
    Code:
    // assumes somewhere there is #define BUFFER_SIZE 200
    int array[BUFFER_SIZE], i;
    
    for(i = 0; i < BUFFER_SIZEE; i++) {
      array[i] = getchar();
    }
    Oops I typed an extra E on BUFFER_SIZE. Good thing this time is the compiler has no idea what I'm talking about and the crisis was averted.

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