menu3.c

《Beginning linux programming》一书相应的源代码

#include <stdio.h>
#include <unistd.h>

char *menu[] = {
    "a - add new record",
    "d - delete record",
    "q - quit",
    NULL,
};

int getchoice(char *greet, char *choices[], FILE *in, FILE *out);

int main()
{
    int choice = 0;
    FILE *input;
    FILE *output;

    if (!isatty(fileno(stdout))) {
        fprintf(stderr,"You are not a terminal, OK.\n");
    }

    input = fopen("/dev/tty", "r");
    output = fopen("/dev/tty", "w");
    if(!input || !output) { 
        fprintf(stderr,"Unable to open /dev/tty\n");
        exit(1);
    }

    do {
        choice = getchoice("Please select an action", menu, input, output);
        printf("You have chosen: %c\n", choice);
    } while (choice != 'q');
    exit(0);
}

int getchoice(char *greet, char *choices[], FILE *in, FILE *out)
{
    int chosen = 0;
    int selected;
    char **option;

    do {
        fprintf(out,"Choice: %s\n",greet);
        option = choices;
        while(*option) {
            fprintf(out,"%s\n",*option);
            option++;
        }
        do {
            selected = fgetc(in);
        } while (selected == '\n');
        option = choices;
        while(*option) {
            if(selected == *option[0]) {
                chosen = 1;
                break;
            }
            option++;
        }
        if(!chosen) {
            fprintf(out,"Incorrect choice, select again\n");
        }
    } while(!chosen);
    return selected;
}