Can't understand the fgets output

Question

In this code I'm letting the users enter how many characters they want to input.

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

int main(void) {

    // Ask the user to enter how many characters you want to write.
    printf("Enter how many characters you want to write. \n");
    int n;
    int itemsRead = scanf_s("%d", &n);

    if (itemsRead != 1) {
        // scanf didn't read the expected input, handle the error
        printf("Error: Input is not in the expected format.\n");
        return 1; // Return a non-zero value to indicate an error
    }
    
    // Clear the input buffer
    int c;
    while ((c = getchar()) != '\n' && c != EOF);

    char *string = NULL;
    string = (char *)malloc(n * sizeof(char));

    if (string != NULL) {
        printf("Enter the string \n");
        fgets(string, n, stdin);
        printf("string is: %s\n", string);
    }

    free(string);
    string = NULL;
}

The problem is: if the user enters 3 characters and subsequently tries to enter 3 characters it only displays the first 2 characters.

Answer 1

Consult the fgets documentation.

Reads at most count - 1 characters from the given file stream and stores them in the character array pointed to by str. Parsing stops if a newline character is found, in which case str will contain that newline character, or if end-of-file occurs. If bytes are read and no errors occur, writes a null character at the position immediately after the last character written to str.

Your call is reading at most n-1 characters. A char array with room for three bytes can only hold a string with two characters owing to the need for a null terminator to make it a valid string.

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

int main(void) {
    // Ask the user to enter how many characters you want to write.
    printf("Enter how many characters you want to write. \n");
    int n;
    int itemsRead = scanf_s("%d", &n);

    if (itemsRead != 1) {
        // scanf didn't read the expected input, handle the error
        printf("Error: Input is not in the expected format.\n");
        return 1; // Return a non-zero value to indicate an error
    }

    // Increment n by one to allow for the null terminator.
    ++n;
    
    // Clear the input buffer
    int c;
    while ((c = getchar()) != '\n' && c != EOF);

    char* string = NULL;
    string = (char*)malloc(n * sizeof(char));
    // Equivalent to:
    // string = (char*)malloc(n);
    // Because sizeof(char) == 1

    if (string != NULL) {
        printf("Enter the string \n");
        fgets(string, n, stdin);
        printf("string is: %s\n", string);
    }

    free(string);
    string = NULL;
}