Previous Implicit Declaration Error In C
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here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of conflicting types for previous declaration of was here this site About Us Learn more about Stack Overflow the company Business note previous declaration of was here Learn more about hiring developers or posting ads with us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask conflicting types for function error c Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 6.2 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign declaring a function in c up note: previous implicit declaration of ‘point_forward’ was here up vote 7 down vote favorite 3 I can't seem to get this recursive function to compile properly, and I'm not sure why. The code is as follows: void point_forward (mem_ptr m) { mem_ptr temp; temp = m->next; if (temp->next != NULL) point_forward(temp); m->next = temp->next; } My compiler returns this: mm.c:134:6: warning: conflicting
C Function Prototype
types for ‘point_forward’ [enabled by default] mm.c:96:2: note: previous implicit declaration of ‘point_forward’ was here c share|improve this question edited Apr 24 '13 at 4:56 Timothy Jones 13.2k23259 asked Apr 24 '13 at 1:54 user2313514 3612 2 please paste what you have in line 96 –İsmet Alkan Apr 24 '13 at 1:57 point_forward(m); –user2313514 Apr 24 '13 at 1:58 That is the only other instance of this function in my code. –user2313514 Apr 24 '13 at 1:59 please move point_forward above line 96. by moving I mean cut and paste –İsmet Alkan Apr 24 '13 at 1:59 you have changed your comment. what's really at the line 96? –İsmet Alkan Apr 24 '13 at 2:01 | show 7 more comments 1 Answer 1 active oldest votes up vote 10 down vote The key is in this: previous implicit declaration of ‘point_forward’ was here On line 96 you have: point_forward(m); // where m is a mem_ptr; Since the compiler hasn't yet seen a function declaration for point_forward(m), it "implicitly defines" (ie, assumes) a function that returns an int: in
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow the company Business Learn more about hiring developers or posting ads with us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 6.2 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up error: conflicting types for '…'; note: previous implicit declaration of '…' was here up vote 0 down vote favorite I http://stackoverflow.com/questions/16182115/note-previous-implicit-declaration-of-point-forward-was-here created a file. C "Sorting.c" that implements several algorithms for sorting an array of integers. Now I have to create a test file that creates random array and performs the various sorting algorithms on these arrays random. Moreover, the time resulting must be written on the terminal and on a text file. I wrote this code: #include
int myvar) to this scope. The variable needs to be declared either within the same set of braces {}, or in an enclosing scope: { int myvar; { /* myvar is still known here */ } } or at the top level (outside ANY set http://aggregate.org/rfisher/Tutorials/CompilingC/compiling2.html of braces) so that it is globally known. In function `main': warning: implicit declaration of function `f' This tells you that the declaration for the function f doesn't occur until after it is called in function main. main will be compiled with the assumption that f returns an int (C is defined that way). If f returns something else, you will see another message later (see the next common error). This warning is resolved by either moving the function f so in c that it occurs before main in the source file, or better yet, by copying f's prototype to a place before main: float f (void); /* Notice the semicolon: this is a prototype */ /* i.e. This is a declaration, not a */ /* for the function f(). */ void main (void) { float a; ... a = f(); ... } float f (void) /* NO semicolon: this is the function def'n */ { ... } ttt.c: At top level: ttt.c:9: warning: conflicting types for type mismatch with previous external decl ttt.c:5: warning: previous external decl of `f' ttt.c:9: warning: type mismatch with previous implicit declaration ttt.c:5: warning: previous implicit declaration of `f' ttt.c:9: warning: `f' was previously implicitly declared to return `int' This tells you that when f() is defined starting about line 9, the type it is declared with differs from that implied by calling it on line 5. Because there was no prototype or definition for f() before it was called on line 5 in main(), it was assumed to return an int as per the C language definition. This is called an implicit declaration. When the definition for f() declared it to return a float, it mismatched with the assumed declaration. The solution is to prototype f() before it is called in main() or to move the definition of f() before main() in the source. See the example in the previous common error. parse error before 'x', where x is some symbol or identifier. This can be many things, including (but not limited to): a missing semicolon at the end of the previous statement. a missing comment delimiter (*/) at the end of the last comment. an undefined macro or type definition (such as using FILE without #including stdio.h). unterminated comment This means that a comment was opened with (/*) but not closed by the end of the file. You are missing the corresponding (*/). This page was last modified .