Engineering Questions with Answers - Multiple Choice Questions
Data Structure MCQ’s – Length of a String using Recursion
1 - Question
Consider the following iterative implementation to find the length of the string:
#include<stdio.h> int get_len(char *s) { int len = 0; while(________) len++; return len; } int main() { char *s = "harsh"; int len = get_len(s); printf("%d",len); return 0; }
Which of the following lines should be inserted to complete the above code?
a) s[len-1] != 0
b) s[len+1] != 0
c) s[len] != ‘\0’
d) s[len] == ‘\0’
View Answer
Answer: c
Explanation: The line “s[len] != ‘\0′” should be inserted to complete the above code.
2 - Question
What is the output of the following code?
#include<stdio.h> int get_len(char *s) { int len = 0; while(s[len] != '\0') len++; return len; } int main() { char *s = "lengthofstring"; int len = get_len(s); printf("%d",len); return 0; }
a) 14
b) 0
c) Compile time error
d) Runtime error
View Answer
Answer: a
Explanation: The program prints the length of the string “lengthofstring”, which is 14.
3 - Question
What is the time complexity of the following code used to find the length of the string?
#include<stdio.h> int get_len(char *s) { int len = 0; while(s[len] != '\0') len++; return len; } int main() { char *s = "lengthofstring"; int len = get_len(s); printf("%d",len); return 0; }
a) O(1)
b) O(n)
c) O(n2)
d) O(logn)
View Answer
Answer: b
Explanation: The time complexity of the code used to find the length of the string is O(n).
4 - Question
What is the output of the following code?
#include<stdio.h> int get_len(char *s) { int len = 0; while(s[len] != '\0') len++; return len; } int main() { char *s = ""; int len = get_len(s); printf("%d",len); return 0; }
a) 0
b) 1
c) Runtime error
d) Garbage value
View Answer
Answer: a
Explanation: The program prints the length of an empty string, which is 0.
5 - Question
Which of the following can be the base case for the recursive implementation used to find the length of a string?
#include<stdio.h> int get_len(char *s) { int len = 0; while(s[len] != '\0') len++; return len; } int main() { char *s = ""; int len = get_len(s); printf("%d",len); return 0; }
a) if(string[len] == 1) return 1
b) if(string[len+1] == 1) return 1
c) if(string[len] == ‘\0’) return 0
d) if(string[len] == ‘\0’) return 1
View Answer
Answer: c
Explanation: “if(string[len] == ‘\0’) return 0” can be used as base case in the recursive implementation used to find the length of the string.
6 - Question
Consider the following recursive implementation used to find the length of a string:
#include<stdio.h> int recursive_get_len(char *s, int len) { if(s[len] == 0) return 0; return ________; } int main() { char *s = "abcdef"; int len = recursive_get_len(s,0); printf("%d",len); return 0; }
Which of the following lines should be inserted to complete the above code?
a) 1
b) len
c) recursive_get_len(s, len+1)
d) 1 + recursive_get_len(s, len+1)
View Answer
Answer: d
Explanation: The line “1 + recursive_get_len(s, len+1)” should be inserted to complete the code.
7 - Question
What is the output of the following code?
#include<stdio.h> int recursive_get_len(char *s, int len) { if(s[len] == 0) return 0; return 1 + recursive_get_len(s, len+1); } int main() { char *s = "abcdef"; int len = recursive_get_len(s,0); printf("%d",len); return 0; }
a) 5
b) 6
c) 7
d) 8
View Answer
Answer: b
Explanation: The above code prints the length of the string “abcdef”, which is 6.
8 - Question
What is the time complexity of the following recursive implementation used to find the length of the string?
#include<stdio.h> int recursive_get_len(char *s, int len) { if(s[len] == 0) return 0; return 1 + recursive_get_len(s, len+1); } int main() { char *s = "abcdef"; int len = recursive_get_len(s,0); printf("%d",len); return 0; }
a) O(1)
b) O(n)
c) O(n2)
d) O(n3)
View Answer
Answer: b
Explanation: The time complexity of the above recursive implementation used to find the length of the string is O(n).
9 - Question
How many times is the function recursive_get_len() called when the following code is executed?
#include<stdio.h> int recursive_get_len(char *s, int len) { if(s[len] == 0) return 0; return 1 + recursive_get_len(s, len+1); } int main() { char *s = "adghjkl"; int len = recursive_get_len(s,0); printf("%d",len); return 0; }
a) 6
b) 7
c) 8
d) 9
View Answer
Answer: c
Explanation: The function recursive_get_len() is called 8 times when the above code is executed.
10 - Question
What is the output of the following code?
#include<stdio.h> int recursive_get_len(char *s, int len) { if(s[len] == 0) return 0; return 1 + recursive_get_len(s, len+1); } int main() { char *s = "123-1-2-3"; int len = recursive_get_len(s,0); printf("%d",len); return 0; }
a) 3
b) 6
c) 9
d) 10
View Answer
Answer: c
Explanation: The above program prints the length of the string “123-1-2-3”, which is 9.