gets() does not work

Question

I have a program written in C and it calls gets() from a switch when a user chooses the option of 3. Here is my code. It does not seem to wait to wait for the user to input something. Rather the program continues in the switch.

void getField();

#include <stdio.h>
#include <string.h>
/*#include "stubs.c"
#include "record.h" */

int debugMode;

void getField(){
    char name[25];
    char address[80];
    int yearofbirth;
    char telno[15];
    int counter = 0;

    if(debugMode == 1){
        printf("***DEBUG*** Entering getField function \n");
    }

    printf("Enter your name:");
    gets(name);

    printf("Name: %s \n", name);
    printf("\n");
}

void main(int argc, char * argv[])
{
    struct record* start = NULL;
    int userChoice;
    debugMode = 0;

    if(argv[1] != NULL){
        if( (strcmp(argv[1], "debug") == 0) && (argv[2] == NULL) ){
            debugMode = 1;
            printf("Welcome, to the personal address book application \n");
        }
        else{
            int i = 0;
            while(argv[i] != NULL){
                printf(argv[i]);
                printf(" ");
                i++;
            }
            printf(": Command not found \n");
            userChoice = 6;
        }
    }

    if(argv[1] == NULL){
        printf("Welcome, to the personal address book application \n");
        userChoice = 0;
    }


    while(userChoice != 6)
    {
        if(debugMode == 1){
            printf("***DEBUG*** Entering do-while loop \n");
        }

        printf("Enter number corresponding number to option below \n\n");   

        printf("1) Add a new record in the database \n");
        printf("2) Modify a record in the database \n");
        printf("3) Print information about a record in the database \n");
        printf("4) Print all information in the database \n");
        printf("5) Delete an existing record from the database \n");
        printf("6) Quit program \n\n >");


        scanf("%d", &userChoice);

        switch(userChoice){

            case 1:
                /*addRecord(start, arrayHolder, arrayHolder, 0, arrayHolder);
                */userChoice = 0;
                break;
            case 2:
                /*modifyRecord(start, arrayHolder, arrayHolder, arrayHolder);
                */userChoice = 0;
                break;
            case 3:
                /*printRecord(start, arrayHolder);
                */userChoice = 0;
                getField();
                break;
            case 4:
                /*printAllRecords(start);
                */userChoice = 0;
                break;
            case 5:
                /*deleteRecord(start, arrayHolder);
                */userChoice = 0;
                break;
            case 6:
                printf("case 6 \n");
                break;
            default:
                printf("default \n");
                userChoice = 0;
                break;
        }

    }
    printf("\n");
}

Answer 1

When you input an option with the scanf() call, you type 2 keys on your keyboard, for example, 3 and ENTER.
The scanf() consumes the '3' but leaves the ENTER hanging in the input buffer.
When, later, you do gets() that ENTER is still in the input buffer and that's what gets() gets.

You have two options:

• clear the input buffer after each scanf()
• clear the input buffer before each gets()

To clear the input buffer use this code:

int clear_input_buffer(void) {
    int ch;
    while (((ch = getchar()) != EOF) && (ch != '\n')) /* void */;
    return ch;
}

Oh! And stop using gets(). gets() is impossible to use safely. Use fgets() instead.