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PO2D arrays. First index wrong, all others correct
 

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    <p>I have a weird problem and I'm not sure how to approach it.</p> <p>I'm reading a 50x50 chars textfile and want to write it into a 50x51 dynamic array (filling the 51th slot with '\0').</p> <p>Afterwards I'm printing the entire array onto the console. It should show 50 lines with 50 chars each, as this was the input.</p> <p>It works quite well too - with the exception of the first line. For some reason is always wrong.</p> <pre><code>#define FIELD_SIZE 50 int main(int argc, char** args){ char* data = ReadFile("start.txt"); char** map = (char**) malloc( FIELD_SIZE ); if(map==NULL) __debugbreak(); { int i; for(i = 0; i &lt; FIELD_SIZE; i+=1){ map[i] = (char*) malloc(FIELD_SIZE+1); if(map[i]==NULL) __debugbreak(); //(FIELD_SIZE+1) in order to skip the '\n' at the end of each line. memcpy( &amp;map[i][0], &amp;data[i*(FIELD_SIZE+1)], FIELD_SIZE); map[i][FIELD_SIZE] = '\0'; } } { int i; for(i = 0; i &lt; FIELD_SIZE; i+=1){ printf("%s\n", map[i]); //&lt;-- prints something bad for i==0 } } free(data); return 0; } </code></pre> <p>Here's how my console looks like after program execution: <img src="https://i.stack.imgur.com/UDEN6.png" alt="enter image description here"> The first line is supposed to be "aaaaaaaaaaaaa..." too. So it seems like a bad pointer or something.</p> <p>If I'm reducing FIELD_SIZE to 20 instead (and reading in a 20x20 text file respectively) it works fine, however.</p> <p>I don't see a connection between the array size and the first index not working though. Since malloc never returned 0 there's no problem with allocation.</p> <p>I'm using VS2010 C++ to compile the program, but I have to limit myself to the C subset.</p>
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    1. COAre you sure your file's all good?
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    2. COThe file is an ANSI-encoded regular text file (with np++). It just contains 20 rows of 20 a's each. Since all but the first row works I don't think the problem directly lies in reading the file. And as I said, if I reduce FIELD_SIZE everything works, so it's not a "hidden" problematic character or similar in the file.
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    3. COAdded image to post so future visitors can understand question even if the referenced image site is no longer valid.
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      1. USJonathan M
 

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