使用 C 中的两个单独函数将字符数组从一个文件复制到另一个文件

Question

I have a task to get a char array from one text file and put this text in another file. I must use two functions. They must look like this:

int writeText(FILE *wp, char text[])
int readText(FILE *wp, char text[], int max)

I must use my own strlen function (_strlen).

In the function readText they said that I must remember to put '\0' at the end and check that I don't put too many signs in the array (more than the array size).

This is my code

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

int _strlen (char *text)
{
    int i;
    for (i = 0; text[i] != '\0'; ++i);    
    return i;
}

int writeText(FILE *wp, char text[])
{
    int len = _strlen(text);
    for (int i = 0; i < len; i++) {
       fputc (text[i], wp);
    }
    return _strlen(text);
}

int readText(FILE *wp, char text[], int max)
{
    int length = _strlen(text);
    int c;
    int i = 0;
    max = 10000;
    while( (c = fgetc(wp)) != EOF && i <= max )
    {
        fputc (text[i], wp);
        i++;
    }
    if (i > max)
    {
        printf("This array is too big.");
    }
    text[i] = '\0';

    return _strlen(text);
}


int main (int argc, char *argv[])
{
    if (argc != 3) {
    printf("You should run program in this way:\n");
    printf("%s file_source file_result\n",argv[0]);
    exit(1);
    }

    int sum;
    const char source[] = "source.txt"; // plik wejściowy
    const char result[] = "result.txt";     // plik wyjściowy
    FILE *wz, *wc;                         // wskaźnik do pliku

    if( (wz= fopen(source,"r")) == NULL) {
        printf("Open error %s\n", source);
        exit(1);
    }
    if( (wc= fopen(result,"w")) == NULL) {
        printf("Open error %s\n",result);
        exit(2);
    }
    char tab1[1000];
    readText(wz, tab1, 1000);
    writeText(wc, tab1);


    int fclose(FILE *wp);
    int fclose(FILE *wc);

}

After I run this program I get something like that:

p\E2\B4&\FF

And I dont know why.

Answer 1

fputc writes a char to a specified stream. You want to read a char and put that char in a char array. Remove fputc and just assign the char from fgetc to the array at the specific index. There is no need to reassign the max variable. As you had it, it would write over memory not assigned to the array if the input file was larger than your array size. You also want the loop to terminate at two less than max if you want to add a null terminating character at max - 1 or the last index in the allocated array.

int readText(FILE *wp, char text[], int max)
{
    int c, i = 0;
    while((c = fgetc(wp)) != EOF && i < max - 1 )
    {
        text[i] = c;
        ++i;
    }

    text[i] = '\0';

    return _strlen(text);
}