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#include <iostream>
using namespace std;
int search(const char* string, const char* searched);
void replace(const char* string, const char* x, const char* y, char* result)
{
int yLen = strlen(y);
int xLen = strlen(x);
while (true)
{
int indX = search(string, x); //14
if (indX == -1)
break;
for (int i = 0; i < indX; i++)
result[i] = string[i];
result += indX;
string += indX + xLen;
for (int i = 0; i < yLen; i++)
result[i] = y[i];
result += yLen;
}
//the rest symbols
while (*string != '\0')
{
*result = *string;
result++;
string++;
}
*result = '\0';
}
//return the first index of searched in str.
int search(const char* str, const char* searched)
{
int len1 = strlen(str);
int len2 = strlen(searched);
for (int i = 0; i < len1 - len2+1; i++)
{
bool found = true;
for (int j = 0; j < len2; j++)
{
if (searched[j] != str[i + j])
{
found = false;
break;
}
}
if (found)
return i;
}
return -1;
}
int countOccurrences(const char* str, const char* searched)
{
int count = 0;
int searchLen = strlen(searched);
int ind = search(str, searched);
while (ind != -1)
{
count++;
str += (ind + searchLen);
ind = search(str, searched);
}
return count;
}
int main()
{
const char* str = "hello friends! You are my best friends. I have no other friends";
const char* x = "friend";
const char* y = "enemy";
int len = strlen(str);
int xOccurrences = countOccurrences(str, x);
char* result = new char[len - xOccurrences*strlen(x) + xOccurrences*strlen(y) + 1];
replace(str, x, y, result);
cout << result << endl;
delete[] result;
}
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