change constant string

Why the following code can be executed successfully in Unix?
Many books say that constant string can't be changed(strings pointed by pointer is constant). And this code can't be executed in some environment indeed, such as windows.

#include<stdio.h>


main()
{ char *str="hello";
  str[3]='A';
     
printf("string:   %s\n",str);
     
          }
ww111697Asked:
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jkrConnect With a Mentor Commented:
>>Why the following code can be executed successfully in Unix?

That depends on the compiler - some place string literals in 'read only' memory areas, causing a segfault. The proper code to apply such a change would be

#include<stdio.h>
#include <string.h>

main()
{

 char *str_const="hello";

 char* str = strdup ( str_const);
 str[3]='A';
   
 printf("string:   %s\n",str);

 free ( str);
   
}

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ozoCommented:
If the program attyempts to modify a string literal,
the behavior is undefined.
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