How to write a console menu in ANSI/ISO C?

Question

I'm trying to create a simple program in c, where the user has to choose between several options:

char command = '1';
while(command!='0') {
    printf("Menu:\n");
    printf("1. First option\n");
    printf("2. Second option\n");
    printf("0. Exit\n");
    printf("Choose: 0,1,2?: ");
    command = getchar();
    while(getchar()!='\n');     
    switch(command) {
        case '0': break;
        case '1': functionCall1(); break; 
        case '2': functionCall2(); break;
    }
}

The problem with my code is, that every second time I enter 1,2 or 0, nothing happens, only the menu prints itself again. With the debugger I can see, that the value of command, after command = getchar() equals '', every second time. I thought that eating the newline character is enough?

Answer 1

Try my customized menu, I implemented it to make my life easier when I work with programs which contains multiple choices operations. Menu is navigable (arrows:up, down, left, right), and for making a selection you only need to press enter key, menu orientation can be set vertically or horizontally, padding can be set to a group of items(childrens), child starting position, and update with delay.

Menu call example (vertically):

int response = menu("OPTIONS","[*]","->",
                    1,3,3,0,5,
                    "PROFILES","ACTIVITY","VIDEO","SOUND","GAMEPLAY");

The most important thing is because function implementation takes only 60 lines of code.

Menu implementation:

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <windows.h>

// LXSoft
// mod: cui/menu_021
// stdarg.h  -> used for variable list of arguments (va_list, va_start ...)
// windows.h -> used for Sleep function, for *nix use unistd.h

typedef unsigned short int usint_t;
// Menu function prototype
int menu(char* name, char* prefix, char* cursor, usint_t orientation,
         usint_t padding, usint_t start_pos, usint_t delay,
         usint_t num_childs, ...);

int main()
{
    int response = menu("OPTIONS","[*]","->",1,3,3,0,5,
                        "PROFILES","ACTIVITY","VIDEO","SOUND","GAMEPLAY");
    switch(response)
    {
        case 1:
            // doSomethingFoo1();
        break;
        case 2:
            //doSomethingFoo2();
        break;
        /*
         * .
         * .
         * .
         * case n:
         * break;
         */
    }
    printf("\nYour choice is: %d", response);
    return 0;
}

// Menu implementation
int menu
(
    char *name,        // Menu name (eg.: OPTIONS)
    char *prefix,      // Menu prefix (eg.: [*])
    char *cursor,      // Menu cursor (eg.: ->)
    usint_t orient,    /*
                        * Menu orientation vertical or horzontal.
                        * 0 or false for horizontal
                        * 1 or true for vertical
                        */
    usint_t padding,   // Menu childrens padding (eg.: 3)
    usint_t start_pos, // Menu set active child (eg.: 1)
    usint_t delay,     // Menu children switch delay
    usint_t childs,    // Number of childrens
    ...                /*
                        * Variable list of arguments char* type.
                        * Name of the childrens.
                        */
)
{
    va_list args;
    int tmp=0,pos;
    char chr;
    usint_t opt=start_pos;
    char* format=malloc
    (
        (
            strlen(name)+strlen(prefix)+strlen(cursor)+
            3+ /* menu suffix (1 byte) and backspace (2 bytes) */
            (2*childs)+ /* newline (2 bytes) times childs */
            (padding*childs)+ /* number of spaces times childs */
            childs*15 /* children name maxlen (15 bytes) times childs*/
        )*sizeof(char)
    );
    do
    {
        if(tmp!=0)chr=getch();
        if(chr==0x48||chr==0x4B)
            (opt>1&&opt!=1)?opt--:(opt=childs);
        else if(chr==0x50||chr==0x4D)
            (opt>=1&&opt!=childs)?opt++:(opt=1);
        else {/* do nothing at this time*/}
        strcpy(format,"");
        strcat(format,prefix);
        strcat(format,name);
        strcat(format,":");
        va_start(args,childs);
        for (tmp=1;tmp<=childs;tmp++)
        {
            (orient)?strcat(format,"\n"):0;
            pos=padding;
            while((pos--)>0) strcat(format," ");
            if(tmp==opt)
            {
                strcat(format,"\b");
                strcat(format,cursor);
            }
            strcat(format,va_arg(args,char*));
        }
        /*if(tmp!=childs)
        {
            fprintf(stderr,"%s: recieved NULL pointer argument,"
                           " child not named", __func__);
            return -1;
        }*/
        Sleep(delay);
        system("cls");
        printf(format);
        va_end(args);
    }while((chr=getch())!=0x0D);
    return opt;
}

Answer 2

May be you should try to use int x as a key to use a desirable command, may be like that:

while(x != 0)
{
    scanf("%d", &x);
    switch (x)
    {
        printf("input '2' to...\n");
        printf("input '3' to...\n");
        printf("input '4' to...\n");
        printf("input '5' to...\n");
        printf("input '6' to...\n");
        case 1:
            head = Enqueue(head);
            break;
        case 2:
            head1 = spisokMagazinovScenoiMensheiZadannoi(head, head1);
            break;
        case 3:
            head1 = udalenieElementa(head1);
            break;
        case 4:
            head1 = addNewMagazin(head1);
            break;
        case 5:
            head1 = addNewMagazin(head1);
            break;
        case 6:
            printToTheFile(head);
            break;

    }
}

I used it in my previous homework. Hope it will be usefull for you