Find character in a string - c++

Question

I cant get the char search to work. The substring function is working but the char search won't provide the right location of the char it is looking for
#include<iostream>
#include <string>
using namespace std;
int charsearch(string searchInto, char ch, int start = 0)
{
int x = 0;
long n = searchInto.length();
for (int i = 1; i < n; i++)
{
cout << ch;
if (searchInto[i] == ch)
{
i = x;
}
else
i++;
}
cout<< x;
return x;
}
int substr(string src, string tosearch, int start = 0)
{
string searchInto = src;
long n = searchInto.size();
long m = tosearch.size();
int ans = -1;
for (int i = start; i < n; ++i)
{
int p = i;
int q = 0;
bool escape = false;
while (p < n && q < m) {
if (searchInto[p] == tosearch[q]) {
if (tosearch[q] == '/' && !escape) {
++q;
} else {
++p; ++q;
}
escape = false;
} else if (!escape && tosearch[q] == '*') {
++q;
while (q < m && p < n && searchInto[p] != tosearch[q]) ++p;
escape = false;
} else if (!escape && tosearch[q] == '?') {
++p; ++q;
escape = false;
} else if (tosearch[q] == '/' && !escape) {
escape = true;
++q;
} else break;
}
if (q == m) {
return i;
}
if (q == m - 1 && tosearch[q] == '*') {
if (q > 0 && tosearch[q - 1] == '/') continue;
else return i;
}
}
return ans;
}
int main()
{
string searchInto, tosearch;
cout<< "Enter string:";
getline(cin, searchInto);
cout << "Looking for :";
getline(cin, tosearch);
if (tosearch.length() < 2)
{
char ch = tosearch.at(0);
cout << "Found at: " <<charsearch(searchInto, ch) << endl;
cout << "Used Char" << endl;
}
else
cout << "Found at: " <<substr(searchInto, tosearch) << endl;
return 0;
}

Answer 1

To find a character in a string, you have two interfaces.
std::string::find will return the position of a character you find:
auto pos = yourStr.find('h');
char myChar = yourStr[pos];
If the character does not exist, then std::string::npos will be returned as the std::size_t returned for position.
stl algorithm std::find, in header algorithm returns an iterator:
auto it = std::find(yourStr.begin(), yourStr.end(), 'h');
char myChar = *it;
If the character does not exist, then it == yourStr.end().

Answer 2

There are some silly mistakes in your CharSearch method. First of all, You have to break the loop when you got your target character. And most importantly you are not assigning x when you are finding the target. Furthermore, there is extra increment of value i inside the loop. I have modified the function. Please check it below
int charsearch(string searchInto, char ch, int start = 0) {
int x = -1;
long n = searchInto.length();
for (int i = start; i < n; i++)
{
cout << ch;
if (searchInto[i] == ch)
{
x = i; // previously written as i = x which is wrong
break; // loop should break when you find the target
}
}
cout<< x;
return x;
}
Please note that,you can either also use find method of string or std::find of algorithm to search in string.

Answer 3

You need to make changes as per this code
int charsearch(string searchInto, char ch, int start = 0)
{
int x = -1; // : change, if return -1, means not found
long n = searchInto.length();
for (int i = start; i < n; i++) // : change
{
cout << ch;
if (searchInto[i] == ch)
{
x = i; // : change
break; // : change
}
}
cout<< x;
return x;
}
Note : This function will return 1st match.