Real lines in C without overflowing buffer. #C #fgets #read-line

read-line-with-prompt.c

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

const int MAX_LINE_SIZE = 10;

int main(int argc, char **argv){

    char line[MAX_LINE_SIZE + 2];

    const char* PROMPT = ">> ";

    do {
        fputs(PROMPT, stdout);
        if (fgets(line, sizeof(line), stdin) == NULL) {
            fputs("\n", stdout);
            break;
        }
        size_t len = strlen(line);
        if (line[len - 1] != '\n') {
            // input exceeds max size: consume remaining line
            while (getchar() != '\n')
                ;
            line[MAX_LINE_SIZE] = '\0';
            len = MAX_LINE_SIZE;
        } else {
            // input is within limits: erase trailing newline
            line[--len] = '\0';
        }
        printf("Line=<%s> Len=%lu=%lu\n", line, len, strlen(line));
    } while (1);

	return 0;
}