Analysis on character constant area

Source: Internet
Author: User

BelowProgramThe compiling environment is GCC.


# Include <stdio. h> # include <string. h> int main () {char * S1 = "hello"; S1 [0] = 'Z'; printf ("% s \ n", S1); Return 0 ;}

There is no compilation error, but the running error is segmentation fault. Because the string "hello" is in the character constant area, the pointer S1 points to the character constant area, and the character constant area cannot be changed, so (S1 [0] = 'Z') this step is incorrect.
In fact, char * S1 = "hello" is equivalent to const char * S1 = "hello"

# Include <stdio. h> # include <string. h> int main () {char S2 [] = "world"; S2 [0] = 'Z'; printf ("% s \ n", S2 ); return 0 ;}

The program is running correctly. The string "world" is stored in the array S2 and can be modified in the stack space.

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