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POstrcmp() and strcat() sequence
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copied!<p>On my way to hone my C skills with a C Pointers literature, I came across this code. In this problem, I am supposed to justify the output. I am familiar with working of <code>strcat()</code> and <code>strcmp()</code>. I know that <code>strcmp()</code> returns 0 when the two strings passed, are same. </p> <pre><code># include <stdio.h> # include <string.h> int main() { static char str1[]="Good"; static char str2[20]; static char str3[20] ="Day"; int l; l = strcmp(strcat(str3, strcpy(str2, str1)), strcat(str3, "good")); printf("%d\n", l); return 0; } </code></pre> <p>The answer provided there is 0, which means that two calculated strings must be same. I tried to solve the statement in multiple steps. </p> <p>First, tried <code>strcat(str3, strcpy(str2, str1))</code>. 'str2' gets changed to "Good", then <code>strcat()</code> changes <code>str3</code> to `DayGood'. My gcc compiler agrees with me so far.</p> <p>Coming to <code>strcat(str3, "good")</code>, since str3 has been changed to <code>DayGood</code> already, <code>strcat</code> changes <code>str3</code> to <code>DayGoodgood</code>.</p> <p>Again, gcc agress with me. </p> <pre><code>int main() { static char str1[]="Good"; static char str2[20]; static char str3[20] ="Day"; int l; printf("%s\n", strcat(str3, strcpy(str2, str1))); printf("%s\n", strcat(str3, "good")); //l = strcmp(strcat(str3, strcpy(str2, str1)), strcat(str3, "good")); //printf("%d\n", l); return 0; } </code></pre> <p>It produces </p> <pre><code>DayGood DayGoodgood </code></pre> <p>I again tried this variation.</p> <pre><code>int main() { static char str1[]="Good"; static char str2[20]; static char str3[20] ="Day"; int l; printf("%s\n", strcat(str3, "good")); printf("%s\n", strcat(str3, strcpy(str2, str1))); //l = strcmp(strcat(str3, strcpy(str2, str1)), strcat(str3, "good")); //printf("%d\n", l); return 0; } </code></pre> <p>It produces.</p> <pre><code>Daygood DaygoodGood </code></pre> <p>In my both test cases, I get two different strings for comparison. Why is then <code>strcmp()</code> is producing a 0 ?</p>

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