Category: C++ Interview Questions

C++// C++ Program for calculating // the length of string #include <iostream> using namespace std; int cal(char* str) { // base condition if (*str == '\0') return 0; else return 1 + cal(str + 1); } int main() { char str[] = "GeeksforGeeks"; cout << cal(str); return 0; }

Output

13

C++// C++ program to check // Whether a given number // Is palindrome or not #include <bits/stdc++.h> using namespace std; bool isPalRec(char str[], int s, int n) { // If there is only one character if (s == n) return true; // If first and last // characters do not match if (str[s] != str[n]) return false; if (s < n + 1) return isPalRec(str, s + 1, n - 1); return true; } bool isPalindrome(char str[]) { int n = strlen(str); if (n == 0) return true; return isPalRec(str, 0, n - 1); } int main() { char str[] = "GeeKeeG"; if (isPalindrome(str)) cout << "Yes"; else cout << "No"; return 0; }

Output

Yes

C++// C++ Program to // Reverse string using // recursion #include <iostream> using namespace std; void reverse_str(string& s, int n, int i) { if (n <= i) { return; } swap(s[i], s[n]); reverse_str(s, n - 1, i + 1); } int main() { string str = "GeeksforGeeks"; reverse_str(str, str.length() - 1, 0); cout << str << endl; }

Output

skeeGrofskeeG

C++// C++ Program to reversea string #include <cstring> #include <iostream> using namespace std; int main() { int len; string str = "GeeksforGeeks"; len = str.size(); cout << "Reverse of the string: "; for (int i = len - 1; i >= 0; i--) { cout << str[i]; } cout << endl; return 0; }

Output

Reverse of the string: skeeGrofskeeG

            1   
          1   1   
        1   2   1   
      1   3   3   1   
    1   4   6   4   1   
  1   5   10   10   5   1 

C++// C++ program to print // Pascal’s Triangle #include <iostream> using namespace std; void printPascal(int n) { int arr[n][n]; for (int line = 0; line < n; line++) { // Every line has number of integers // equal to line number for (int i = 0; i <= line; i++) { // First and last values in every row are 1 if (line == i || i == 0) arr[line][i] = 1; else arr[line][i] = arr[line - 1][i - 1] + arr[line - 1][i]; cout << arr[line][i] << " "; } cout << "\n"; } } int main() { int n = 6; printPascal(n); return 0; }

Output

1 
1 1 
1 2 1 
1 3 3 1 
1 4 6 4 1 
1 5 10 10 5 1 

1
2 3
4 5 6
7 8 9 10

C++// C Program to print the Floyd's Triangle #include <stdio.h> int main() { int rows = 4; int n = 1; // outer loop to print all rows for (int i = 0; i < rows; i++) { // innter loop to print abphabet in each row for (int j = 0; j <= i; j++) { printf("%d ", n++); } printf("\n"); } return 0; }

Output

1 
2 3 
4 5 6 
7 8 9 10 

C++// C++ Program to print a triangle star patter #include <iostream> using namespace std; int main() { int rows; rows = 5; for (int i = 1; i <= rows; i++) { for (int j = 1; j <= i; j++) { cout << "*"; } cout << endl; } return 0; }

Output

*
**
***
****
*****

C++// C++ Program to print inverted pyramid #include <iostream> using namespace std; int main() { int rows = 5; for (int i = rows; i >= 1; i--) { for (int j = rows; j > i; j--) { cout << " "; } for (int k = 1; k <= (2 * i - 1); k++) { cout << "*"; } cout << endl; } return 0; }

Output

*********
 *******
  *****
   ***
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