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    <p>The parameters does not match up with the variable names.</p> <ul> <li>sPhrase is declared as an array of chars.</li> <li>The function <code>reverse</code> has a parameter <code>sPhrase</code> which is a pointer to an array of chars</li> </ul> <p>This explains why there is a 'type mismatch'. I have included a fixed version, try that.</p> <pre> char* reverse(char *sPhrase); int main() { char sPhrase[STRMAX]; char sReverse[STRMAX]; printf("Enter string (max. 50 chars): "); gets(sPhrase); sReverse = reverse(sPhrase); return 0; } char* reverse(char* sPhrase) { /* <strike>char* sOutput[STRMAX];</strike>*/ static char sOutput[STRMAX]; int iCnt = 0, iCntRev; for (iCntRev = strlen(sPhrase)-2; iCntRev >= 0; iCntRev--) { sPhrase[iCnt] = sOutput[iCntRev]; iCnt++; } sPhrase[iCnt] = '\0'; // Don't forget to close the string return sOutput; } </pre> <p>The compiler is pretty smart to check for 'incompatible' types. C is <strike>strict</strike> very relaxed when it comes to this kind of thing, so the onus is on you on making sure the declarations match up with the definitions in order for a successful compile.</p> <p>I have also corrected the problem with using the <code>sOutput</code> variable within the <code>reverse</code> function, and changed it to a <code>static</code> as the variable will go out of scope and will end up with garbage, by prefixing the keyword <code>static</code> will ensure that the variable remains in scope.</p> <p><strong>Edit:</strong> For some reason, I added the strike tag to strike out the line but others are seeing it somehow...???</p> <p>On closer inspection, the code does not work, I have fixed it, taking into account of other people's inputs and consideration, note I have used <code>fgets</code> instead of the evil <code>gets</code> function as that is a breeding ground for buffer overflows, also changed the function signature to use the <code>const</code> keyword for the parameter.</p> <pre> char * reverse(const char *sPhrase); int main() { char sPhrase[STRMAX]; char *sReverse; printf("Enter string (max. 50 chars): "); fgets(sPhrase, STRMAX - 1, stdin); sReverse = reverse(sPhrase); printf("Reversed string: %s\n", sReverse); return 0; } char *reverse(const char* sPhrase) { char* sOutput; int iCnt = 0, iCntRev; sOutput = (char *)malloc((STRMAX * sizeof(char)) + 1); if (sOutput){ for (iCntRev = strlen(sPhrase) - 1; iCntRev &gt;= 0; iCntRev--) { *sOutput++ = sPhrase[iCntRev]; iCnt++; } *sOutput++ = '\0'; } return (sOutput - iCnt); } </pre> <p>Here's an excellent <a href="http://home.netcom.com/~tjensen/ptr/pointers.htm" rel="nofollow noreferrer">tutorial</a> on pointers.</p> <p>Hope this helps, Best regards, Tom.</p>
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    1. POC: problem with char*
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    1. USt0mm13b
    1. USt0mm13b
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    1. COThis is incorrect. sOutput is allocated on the stack, so **cannot be returned** without introducing undefined behaviour.
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      1. USBlueRaja - Danny Pflughoeft
    2. CO@BlueRaja: fixed it!
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    3. COAnd it *still* misdeclares `sOutput`. Either `char sOutput[STRMAX]` *or* `char * sOutput` (plus a malloc), but not `char * sOutput[STRMAX]`.
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      1. UST.J. Crowder
 

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