Question

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

int main()
{
int a = 0, len1 = 0, len2 = 0;
int BUFSIZE = 1000;
char *string1[1];
char *string2[1];
FILE *fp1 = fopen("input1.txt", "r");
FILE *fp2 = fopen("input2.txt", "r");
if ((fp1 == 0)||(fp2 == 0))
{
    fprintf(stderr, "Error while opening");
    return 0;
}
string1[a] = (char *)malloc(BUFSIZE);
string2[a] = (char *)malloc(BUFSIZE);
fgets(string1[0], BUFSIZE, fp1);
fgets(string2[0], BUFSIZE, fp2);
len1=strlen(string1[0]);
len2=strlen(string2[0]);

printf("%c\n", string1[0][4]);
printf("Output: \n");
srand(time(NULL));
printf("%s\n", string1[0]);
printf("%s\n", string2[0]);
printf("\n");
printf("%d %d", len1, len2); 
printf("\n");

free(string1[0]);
free(string2[0]);
int x=0;
scanf("%d", &x);
fclose(fp1);
fclose(fp2);
return 0;
}

I need to read a string from a file and store it in an array. I need to read only one line of string, and each element of the array should be a character of the string. For example, if I read ‘ABCDABC’ into an array, then array[3] should be ‘D’. But I don’t really know how to do it, I modified some other’s code, and get the above code. But I don’t want to involve pointers and address stuff in my code. So could anyone tell me how to realize it without using pointers? Thank you!

Answer 1

Instead of char * and malloced memory, you can also use plain char[N]. The changes are small, since a char[N] is automatically converted to a pointer to its first element when it is passed to a function (likje fgets or strlen). The code would also only minimally change if you used plain char* for string1 and string2, char *string1 = malloc(BUFSIZE);, the main difference here would be the malloc and the free at the end.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main()
{
    int a = 0, len1 = 0, len2 = 0;
    int BUFSIZE = 1000;

    // char *string1;
    // char *string2;

    // instead of one-element arrays of char*, let's just use char arrays

    char string1[BUFSIZE];
    char string2[BUFSIZE];

    // One pointer to check whether fgets succeeded
    char *suc;

    FILE *fp1 = fopen("input1.txt", "r");
    FILE *fp2 = fopen("input2.txt", "r");
    if ((fp1 == 0)||(fp2 == 0))
    {
        fprintf(stderr, "Error while opening");
        return 0;
    }
    // No need for malloc, we have char arrays
    // string1 = (char *)malloc(BUFSIZE);
    // string2 = (char *)malloc(BUFSIZE);
    suc = fgets(string1, BUFSIZE, fp1);
    if (!suc) {
        // fgets failed, what now? exit?
        return EXIT_FAILURE;
    }
    suc = fgets(string2, BUFSIZE, fp2);
    if (!suc) {
        // see above
        return EXIT_FAILURE;
    }
    len1=strlen(string1);
    len2=strlen(string2);

    // is the read string long enough?
    if (len1 > 4) {
        printf("%c\n", string1[4]);
    }
    printf("Output: \n");
    srand(time(NULL));
    printf("%s\n", string1);
    printf("%s\n", string2);
    printf("\n");
    printf("%d %d", len1, len2); 
    printf("\n");

    // free is only for m/c/re-alloced memory
    // free(string1);
    // free(string2);
    int x=0;
    scanf("%d", &x);
    fclose(fp1);
    fclose(fp2);
    return 0;
}