memset zero 2d array big ISO warning ... how to rid of it?

every sense I just put
gcc -Wall -Wextra -Wpedantic -lm -o "%e" "%f"
in my line I get this now.

Code:

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gcc -Wall -Wextra -Wpedantic -lm -o "find_the_spywords" "find_the_spywords.c" (in directory: /home/userx/bin)
find_the_spywords.c: In function 'main':
find_the_spywords.c:62:4: warning: ISO C forbids zero-size array [-Wpedantic]
    memset(keyword, 0, 10 * 50 * sizeof(char[0][0]));
    ^
find_the_spywords.c:62:4: warning: ISO C forbids zero-size array [-Wpedantic]
find_the_spywords.c:85:2: warning: ISO C forbids zero-size array [-Wpedantic]
  memset(spywords, 0, 10 * 50 * sizeof(char[0][0]));
  ^
find_the_spywords.c:85:2: warning: ISO C forbids zero-size array [-Wpedantic]
Compilation finished successfully.

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so what is the real way to properly zero a 2d char array , or any 2d array for that matter?

Code:

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char spywords[10][50];
 memset(spywords, 0, 10 * 50 * sizeof(char[0][0]));

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If the compiler knows the size of the array, you can do:

Code:

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memset(spywords, 0, sizeof(spywords));

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This code of course wouldn't work with dynamically allocated arrays. The size needs to be known at compile-time. An exception to this though are variable-length arrays, for which sizeof is evaluated at run-time.

Quote:

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Originally Posted by GReaper

If the compiler knows the size of the array, you can do:

Code:

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memset(spywords, 0, sizeof(spywords));

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This code of course wouldn't work with dynamically allocated arrays. The size needs to be known at compile-time. An exception to this though are variable-length arrays, for which sizeof is evaluated at run-time.

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thanks and,
humm ( something to think about )to the second part...

It would perhaps be preferred to do for (size_t i = 0; i < rowsize; i++) memset(spywords[i], 0, colsize); especially if the data structure is on the heap.

Since a C string is defined as a sequence followed by literal zero as well, you could also make a similar loop and simply assign spywords[i][0] = '\0';

Quote:

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Originally Posted by whiteflags

It would perhaps be preferred to do for (size_t i = 0; i < rowsize; i++) memset(spywords[i], 0, colsize); especially if the data structure is on the heap.

Since a C string is defined as a sequence followed by literal zero as well, you could also make a similar loop and simply assign spywords[i][0] = '\0';

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that is what I am accustom to, initializing array in a loop. but with this new fanged memset, I may have gone a little memset happy. :D
thanks for your input.