C++ Segfault when comparing two characters?

Question

It says the segfault occurs on the 5th line.
strcmp() will not work for here because it needs to be a const char.
It uses SDL but I don't think that has anything to do with the problem.


void pstr(const char str[], int x, int y, SDL_Surface* scr, SDL_Surface* chars){
int i;
int len = sizeof(str);
do{
if(str[i]=='a'){pchar(0,0,x+(i*8),y,scr,chars);};
//...
//... This here is just similar to the line above.
//...
}while(i};


I'm building it with g++ if that makes any difference.

Answer 1

You need to initialize i to 0. As it is, it will be a random value that isn't a valid index into str, which is why you fault.



Also, I'm pretty sure you don't want to set len to sizeof(str). Since str is a pointer (char str[] is equivalent to char *str), sizeof(str) will be sizeof a pointer, which is probably 4 on your system. If it doesn't make sense to always set len to 4, then you don't want sizeof. You probably want strlen(str), assuming str is a properly nul terminated string.

Answer 2

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Answer 3

While we're at it, when you're already using C++ don't use char* as strings, use std::string instead.

Answer 4

You didn't initialize i to anything. Are you sure that's what you intended to do?