How to remove trailing newline character from fgets input?

There are many ways to remove the trailing newline character from fgets input. Below I am mentioning some ways to remove the trailing newline character from the fgets input. You can use any one of them as per your requirement.

But here I want to mention that in the below solution some are the compliant solution and some are the non-compliant solutions.

Method 1:

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

#define  BUFFER_SIZE 24

int main(void)
{
    char buf[BUFFER_SIZE];

    printf("Enter the data = ");

    if (fgets(buf, sizeof(buf), stdin) == NULL)
    {
        printf("Fail to read the input stream");
    }
    else
    {
        buf[strlen(buf) - 1] = '\0';
    }

    printf("Entered Data = %s\n",buf);

    return 0;
}

Explanation: The strlen() function computes the length of a string by determining the number of characters that precede the terminating null character. A problem occurs if the first character read from the input by fgets() happens to be a null character. This may occur, for example, if a binary data file is read by the fgets(). If the first character in buf is a null character, strlen(buf) returns 0, the expression strlen(buf) – 1 wraps around to a large positive value, and a write-outside-array-bounds error occurs.

Method 2:

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

#define  BUFFER_SIZE 24

int main(void)
{
    char buf[BUFFER_SIZE];

    printf("Enter the data = ");

    if (fgets(buf, sizeof(buf), stdin) == NULL)
    {
        printf("Fail to read the input stream");
    }
    else
    {
        //find new line
        char *ptr = strchr(buf, '\n');
        if (ptr)
        {
            //if new line found replace with null character
            *ptr  = '\0';
        }
    }
    printf("Entered Data = %s\n",buf);

    return 0;
}

Explanation: In the above C program strchr() (string function) replace the newline character in the string with ‘\0’ if it exists.

Method 3:

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

#define  BUFFER_SIZE 24

int main(void)
{
    char buf[BUFFER_SIZE];

    printf("Enter the data = ");

    if (fgets(buf, sizeof(buf), stdin) == NULL)
    {
        printf("Fail to read the input stream");
    }
    else
    {
        buf[strcspn(buf, "\n")] = '\0';
    }
    printf("Entered Data = %s\n",buf);

    return 0;
}

Explanation: The strcspn() calculates the length of the number of characters before the 1st occurrence of character present in both the string. Because we have given “\n” as a second-string so we will get the length of the string before the “\n”. Now we put the ‘\0’ in place of ‘\n’.

Method 4:

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

#define  BUFFER_SIZE 24

int main(void)
{
    char buf[BUFFER_SIZE];

    printf("Enter the data = ");

    if (fgets(buf, sizeof(buf), stdin) == NULL)
    {
        printf("Fail to read the input stream");
    }
    else
    {
        strtok(buf,"\n");
    }
    printf("Entered Data = %s\n",buf);

    return 0;
}

Note: strtok is not safe to use. You can use strtok_r in place of strtok.

Method 5:

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

#define  BUFFER_SIZE 24

void removeNewLineChar(char *ptr)
{
    while((ptr != NULL) && (*ptr != '\n'))
    {
        ++ptr;
    }

    *ptr = '\0';
}

int main(void)
{
    char buf[BUFFER_SIZE];

    printf("Enter the data = ");

    if (fgets(buf, sizeof(buf), stdin) == NULL)
    {
        printf("Fail to read the input stream");
    }
    else
    {
      removeNewLineChar(buf);
    }
    printf("Entered Data = %s\n",buf);

    return 0;
}

Explanation: In this C program I am finding the position of ‘\n’ using the while loop and placing the null character ( ‘\0’). But you need to use this code very carefully.

Note: Some of the compliant solution and some Noncompliant solution. It is up to you which you want to use in your C program.