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Nov 15th, 2007

Function syntax to take in a char array and return keyboard input

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Hey everyone,

I'm working on function that will take in a char array, prompt the user to input a string, and then return that string to the function. Below is what I've been working on and yes, I know it is not the right syntax, but I'm hoping someone could help me fix it so it works. Thanks!

-Barefoot

C Syntax (Toggle Plain Text)
char getString(char)
 
int main() {
    char string[200];
    string = getString(string);
}
 
char getString(char string) {
    scanf("%s",string);
    return string;
}
char getString(char)

int main() {
    char string[200];
    string = getString(string);
}

char getString(char string) {
    scanf("%s",string);
    return string;
}

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Barefootsanders

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Nov 15th, 2007

Re: Function syntax to take in a char array and return keyboard input

You are on the right track. The only problem is that char is a single character, not a whole list of them (or array of them). You probably want to use a pointer to an array of chars.

Also, don't use %s in scanf() without qualifying it with a maximum width.

C Syntax (Toggle Plain Text)
char *getString(char *string);
 
int main() {
    char string[200];
    getString(string);
}
 
char *getString(char *string) {
    scanf("%200s",string);
    return string;
}
char *getString(char *string);

int main() {
    char string[200];
    getString(string);
}

char *getString(char *string) {
    scanf("%200s",string);
    return string;
}

You can pass the length of the target string into the function if you want:

C Syntax (Toggle Plain Text)
char *getString( char *string, int length ) {
  char format[ 30 ];
  sprintf( format, "%%%ds", length );
  scanf( format, string );
  return string;
  }
char *getString( char *string, int length ) {
  char format[ 30 ];
  sprintf( format, "%%%ds", length );
  scanf( format, string );
  return string;
  }

Hope this helps.

Duoas

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Postaholic

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Nov 15th, 2007

Re: Function syntax to take in a char array and return keyboard input

Study the interface which fgets() provides.

Salem

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Posting Sage

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Nov 15th, 2007

Re: Function syntax to take in a char array and return keyboard input

Click to Expand / Collapse Quote originally posted by Duoas ...

You are on the right track. The only problem is that char is a single character, not a whole list of them (or array of them). You probably want to use a pointer to an array of chars.

Also, don't use %s in scanf() without qualifying it with a maximum width.
C Syntax (Toggle Plain Text)
char *getString(char *string);
 
int main() {
    char string[200];
    getString(string);
}
 
char *getString(char *string) {
    scanf("%200s",string);
    return string;
}
char *getString(char *string); int main() { char string[200]; getString(string); } char *getString(char *string) { scanf("%200s",string); return string; }

Ahh, thanks. Worked like a charm. Exactly what I needed.

Barefootsanders

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Nov 15th, 2007

Re: Function syntax to take in a char array and return keyboard input

> Worked like a charm. Exactly what I needed.
That's a shame, considering that there's a bug in the code.
Let's see if other people can spot it.

Salem

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Nov 15th, 2007

Re: Function syntax to take in a char array and return keyboard input

Click to Expand / Collapse Quote originally posted by Salem ...

> Worked like a charm. Exactly what I needed.
That's a shame, considering that there's a bug in the code.
Let's see if other people can spot it.

sorry, I should have said I changed it to this,

C Syntax (Toggle Plain Text)
char *getString(char *string) {
	scanf("%199s",string);
	return string;
}
char *getString(char *string) {
	scanf("%199s",string);
	return string;
}

to provide for the null char. Thanks again

Barefootsanders

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Nov 15th, 2007

Re: Function syntax to take in a char array and return keyboard input

Click to Expand / Collapse Quote originally posted by Barefootsanders ...

sorry, I should have said I changed it to this,
C Syntax (Toggle Plain Text)
char *getString(char *string) {
	scanf("%199s",string);
	return string;
}
char *getString(char *string) { scanf("%199s",string); return string; }
to provide for the null char. Thanks again

We still recommend:

(Toggle Plain Text)

char *getString(char *string) {
	fgets(string, 200,stdio);
	return string;
}

It's just too easy to make a mistake with scanf() . And why do you need to pull in the and execute the parsing for %d, %u, %i, %g, etc when fgets() requires nothing extra but reading a string. Safely.

WaltP

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Posting Sage

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Nov 16th, 2007

Re: Function syntax to take in a char array and return keyboard input

Yet still, the size of the buffer which is being written to isn't being passed as a parameter.
*shrug*

Salem

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