使用 atoi() 并打印字符串失败 - C

Question

I want to write a program that it will read a couple of strings, convert one of them to an integer using the atoi() and then printing another.

This is my code:

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define N 3

int main() {
    char Name[N][20], Sname[N][20], afm[N][5];
    int i = 0;
    char slash;
    int date, month, year;
    int afmi;

    while (1) {

        printf("Give a 5-digit number: ");
        gets(afm[i]);

        afmi = atoi(afm); //Converting the afm string to an integer

        if (afmi == 0) { /*Getting out of the while loop as soon as the afm                                                              string gets 0 as an input. */
            break;
        }

        printf("Give your name: ");
        gets(Name[i]);

        printf("Give your Surname: ");
        gets(Sname[i]);

        printf("Birth date: "); //dd/mm//yy format
        scanf("%d%c%d%c%d", &date, &slash, &month, &slash, &year);
        getchar();


        i++;
    }

    for (i = 0; i <= N+1; i++) {  /*Here i want to print all the names i have input, one under another*/ 
        printf("name: %s \n", Name);
    }

    system("pause");
    return 0;
}

So my problem is that it doesnt exit the while loop if i enter 0 as an input the second time i do the process. Moreover, it does not print the names correctly in the end... What can i do? (Take in consideration that i am an amateur :D) Thank you for your help!

Answer 1

Insufficient space for the string. @barak manos

When the following code attempts to read 5 char into afm[i] , it invokes undefined behavior as a keyboard entry of 5 char like "abcde" and Enter , attempts to store 'a' , 'b' , 'c' , 'd' , 'e' , '\\0' into afm[i] .

// Bad code
#define N 3
char afm[N][5];
    printf("Give a 5-digit number: ");
    gets(afm[i]);

The above is a an example of the problem of using gets() , which is no longer standard in C11.

Instead use fgets() .

  printf("Give a 5-digit number: ");
  char buf[80];
  if (fgets(buf, sizeof buf, stdin) == NULL) Handle_EOF();
  afmi = atoi(buf);  // or strtol() for better error handling.