C read file line by line

Question

I wrote this function to read a line from a file:

const char *readLine(FILE *file) {

    if (file == NULL) {
        printf(\"Error: file pointer is null.\"         


        

Answer 1

A complete, fgets() solution:

#include 
#include 

#define MAX_LEN 256

int main(void)
{
    FILE* fp;
    fp = fopen("file.txt", "r");
    if (fp == NULL) {
      perror("Failed: ");
      return 1;
    }

    char buffer[MAX_LEN];
    // -1 to allow room for NULL terminator for really long string
    while (fgets(buffer, MAX_LEN - 1, fp))
    {
        // Remove trailing newline
        buffer[strcspn(buffer, "\n")] = 0;
        printf("%s\n", buffer);
    }

    fclose(fp);
    return 0;
}

Output:

First line of file
Second line of file
Third (and also last) line of file

Remember, if you want to read from Standard Input (rather than a file as in this case), then all you have to do is pass stdin as the third parameter of fgets() method, like this:

while(fgets(buffer, MAX_LEN - 1, stdin))

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_Appendix

Removing trailing newline character from fgets() input

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