This is an extension of recommendation:

STR30-C. Do not attempt to modify string literals

Since string literals are constant, they should only be assigned to constant pointers as indicated below:

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By assigning string literals to constant pointers the compiler will warn you if you try to modify them. 

Making code reverse compatible to fit this standard sometimes breaks functionality but this is a good recommendation to follow on new code 

References:

http://www.open-std.org/jtc1/sc22/wg21/docs/papers/1993/N0389.asc;

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