gets() function throw exception?

Question

void getInputWith_gets()
{
    char firstName[5];
    char lastName[5];
    printf("Enter your first name: ");
    gets(firstName);
    printf("Enter your last name: ");
    gets(lastName);
    printf("Hello, %s, %s\n", firstName, lastName);
}

int main(int argc, char **argv)
{
    getInputWith_gets();
    //getInputWith_fgets();
    system("pause");
    return 0;
}

I am using MS Visual Studio 2017, I know the restriction of using the "gets()" function that I have a maximum of 5 chars to be entered but if I entered exactly 5 characters, the console prints correctly(and doesn't print "press any key to continue... due to "system("pause") statment") but the program get stuck at the debugger screen and after the last "printf" statement I get a a red error symbol with a pop-up saying: "Run-Time Check Failure #2 - Stack around the variable 'lastName' was corrupted." does this means that the "gets()" function will read 5 exclusive characters only?

Answer 1

You have multiple bugs here:

• In ancient, obsolete C where gets existed, you must #include <stdio.h> or otherwise you might get weird run-time behavior, since ancient obsolete C allowed functions with no prototype.
• In modern and semi-modern C, the function gets is removed/flagged obsolete and should never be used. See Why is the gets function so dangerous that it should not be used? and also What are the functions from the standard library that must/should be avoided?.
• Strings in C are null terminated, meaning you have to leave room for the null terminator.

Also note that the function format void getInputWith_gets() is obsolete style, you should be writing void getInputWith_gets(void).

Overall, it seems you are learning C from a completely outdated source (over 20 years outdated).