Access violation with C++ -

i bit rusty c languages, , have been asked write quick little application take string stdin , replace every instance of letter 'a' letter 'c'. feel logic spot on (largely reading posts on site, might add), keep getting access violation errors.

here code:

#include <stdio.h> #include <string.h> #include <iostream> #include <algorithm> using namespace std;  int main() {     printf("enter string:\n");     string txt;     scanf("%s", &txt);     txt.replace(txt.begin(), txt.end(), 'a', 'c');     txt.replace(txt.begin(), txt.end(), 'a', 'c');     printf("%s", txt);     return 0; } 

i can use insight. thank much!

scanf doesn't know std::string is. c++ code should this:

#include <string> #include <iostream> #include <algorithm> using namespace std;  int main() {     cout << "enter string:" << endl;     string txt;     cin >> txt;     txt.replace(txt.begin(), txt.end(), 'a', 'c');     txt.replace(txt.begin(), txt.end(), 'a', 'c');     cout << txt;     return 0; }