Thread: Compile Error:

  1. #1
    Registered User
    Join Date
    May 2006

    Compile Error:

    here's my compile error.
    $ cc fig07_10.c
    /tmp/cc5AugyJ.o: In function `main':
    fig07_10.c:(.text+0x69): undefined reference to `convertToUpperCase'
    collect2: ld returned 1 exit status
    #include <stdio.h>
    #include <ctype.h>
    void convertToUpperCase( char * );
    int main()
    	char string[] = "characters and $32.98";
    	printf( "The string before conversion is: &#37;s", string );
    	convertToUpperCase( string );
    	printf( "\nThe string after conversion is: %s\n", string );
    	printf( "\nThe string after conversion is: %s\n",  string );
    	return 0;
    void convertToUppercase( char *sPtr )
    	while ( *sPtr != '\0' ) {
    		if ( islower( *sPtr ) )
    			*sPtr = toupper( *sPtr );

    I think gcc needs an extra argument but I don't understand why or what it is.

  2. #2
    and the Hat of Guessing tabstop's Avatar
    Join Date
    Nov 2007
    Quote Originally Posted by yougene View Post

    void convertToUpperCase( char * );
    void convertToUppercase( char *sPtr )
    Compare and contrast.

  3. #3
    Join Date
    Oct 2007
    Inside my computer
    void convertToUpperCase( char * );
    ...should also be...
    void convertToUpperCase(char* sPtr);
    Anything else is just bad practice. Do not leave out the parameter names in the prototypes.
    Quote Originally Posted by Adak View Post
    io.h certainly IS included in some modern compilers. It is no longer part of the standard for C, but it is nevertheless, included in the very latest Pelles C versions.
    Quote Originally Posted by Salem View Post
    You mean it's included as a crutch to help ancient programmers limp along without them having to relearn too much.

    Outside of your DOS world, your header file is meaningless.

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