CODEWITHSUNDEEP
cswap
Martin
Martin

Reputation: 40573

Swap function for a char*

I have the simple function below which swap two characters of an array of characters (s). However, I am getting a "Unhandled exception at 0x01151cd7 in Bla.exe: 0xC0000005: Access violation writing location 0x011557a4." error. The two indexes (left and right) are within the limit of the array. What am I doing wrong?

void swap(char* s, int left, int right) {
    char tmp = s[left];
    s[left] = s[right];
    s[right] = tmp;
}

swap("ABC", 0, 1);

I am using VS2010 with unmanaged C/C++. Thanks!

Upvotes: 3

Views: 4300

Answers (2)

wenlujon
wenlujon

Reputation: 693

"ABC" is in the RODATA section, so you can't change it, please see the assembly:

        .section        .rodata
.LC0:
        .string "ABC"

Upvotes: 1

Evan Teran
Evan Teran

Reputation: 90422

You can't modify a string literal. instead try this:

char s[] = "ABC"
swap(s, 0, 1);
printf("%s\n", s);

Upvotes: 8

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