String tokenizer

#1

What is the meaning of “str.c_str()” in line number 7 of Prateek bhaiya’s code?
It would be better if you can explain me the whole line number 7 once.

#2

post the code once here .

#5

#include
#include
#include
using namespace std;

string extractStringAtKey(string str, int key) {
//strtok
char *s = strtok((char *)str.c_str(), " ");
while (key > 1) {
s = strtok(NULL, " ");
key–;
}
return (string)s;
}
int convertToInt(string s) {
int ans = 0;
int p = 1;
for (int i = s.length() - 1; i >= 0; i–) {
ans += ((s[i] - ‘0’) * p);
p = p * 10;
}
return ans;

}

bool numericCompare(pair<string, string> s1, pair<string, string> s2) {
string key1, key2;
key1 = s1.second;
key2 = s2.second;

return convertToInt(key1) < convertToInt(key2);

}
bool lexicoCompare(pair<string, string> s1, pair<string, string> s2) {
string key1, key2;
key1 = s1.second;
key2 = s2.second;

return key1 < key2;

}

int main() {

int n;
cin >> n;
cin.get();

string a[100];
for (int i = 0; i < n; i++) {
	getline(cin, a[i]);
}

int key;
string reversal, ordering;
cin >> key >> reversal >> ordering;

pair<string, string> strPair[100];



for (int i = 0; i < n; i++) {

	strPair[i].first = a[i];
	strPair[i].second = extractStringAtKey(a[i], key);
}

//Next = sorting

if (ordering == "numeric") {
	sort(strPair, strPair + n, numericCompare);
}
else {
	sort(strPair, strPair + n, lexicoCompare);
}

//Reversal
if (reversal == "true") {
	for (int i = 0; i < n / 2; i++) {
		swap(strPair[i], strPair[n - i - 1]);
	}
}

//Print the output
for (int i = 0; i < n; i++) {
	cout << strPair[i].first << endl;
}

return 0;

}

#6

@yobasu2015

  1. str.c_str() - https://www.geeksforgeeks.org/basic_string-c_str-function-in-c-stl/
  2. strtok() - https://www.geeksforgeeks.org/strtok-strtok_r-functions-c-examples/
    If you need help with anything after this then please let me know
    Else please close the doubt