Synopsis

Detect and handle standard library errors.

Enabled by default

Yes

Severity/Certainty

High/High

Full description

The majority of the standard library functions, including I/O functions and memory allocation functions, return either a valid value or a value of the correct return type that indicates an error (for example, -1 or a null pointer). It is essential that programs detect and appropriately handle all errors in accordance with an error-handling policy. This check warns on usage of file char I/O standard library functions without checking for errors when the return value is EOF.

Coding standards

Code examples

The following code example fails the check and will give a warning:

#include <stdio.h>

int main()
{
    FILE *fp = fopen("test.txt", "r");
    int ch = getc(fp);
    while (ch != EOF)
        {
            /* display contents of file on screen */
            putchar(ch);

            ch = getc(fp);
        }

    fclose(fp);

    getchar();
    return 0;
}

The following code example passes the check and will not give a warning about this issue:

#include <stdio.h>

int main()
{
    FILE *fp = fopen("test.txt", "r");
    int ch = getc(fp);
    while (ch != EOF)
        {
            /* display contents of file on screen */
            putchar(ch);

            ch = getc(fp);
        }

    if (feof(fp))
        printf("\n End of file reached.");
    else
        printf("\n Something went wrong.");
    fclose(fp);

    getchar();
    return 0;
}