Strings

Which of the following function is correct that finds the length of a string?

A.	int xstrlen(char s) { int length=0; while(s!='\0') { length++; s++; } return (length); }
B.	int xstrlen(char s) { int length=0; while(*s!='\0') length++; s++; return (length); }
C.	int xstrlen(char s) { int length=0; while(s!='\0') length++; return (length); }
D.	int xstrlen(char s) { int length=0; while(s!='\0') s++; return (length); }

Answer: Option A

Explanation:

Option A is the correct function to find the length of given string.

Example:

#include<stdio.h>

int xstrlen(char *s)
{
    int length=0;
    while(*s!='\0')
    { length++; s++; }
    return (length);
}

int main()
{
    char d[] = "IndiaBIX";
    printf("Length = %d\n", xstrlen(d));
    return 0;
}

Output: Length = 8

Which of the following function is more appropriate for reading in a multi-word string?

A.	printf();
B.	scanf();
C.	gets();
D.	puts();

Answer: Option C

Explanation:

gets(); collects a string of characters terminated by a new line from the standard input stream stdin

#include <stdio.h>

int main(void)
{
   char string[80];

   printf("Enter a string:");
   gets(string);
   printf("The string input was: %s\n", string);
   return 0;
}

Output:

Enter a string: IndiaBIX

The string input was: IndiaBIX

Which of the following function is used to find the first occurrence of a given string in another string?

A.	strchr()
B.	strrchr()
C.	strstr()
D.	strnset()

Answer: Option C

Explanation:

The function strstr() Finds the first occurrence of a substring in another string

Declaration: char *strstr(const char *s1, const char *s2);

Return Value:
On success, strstr returns a pointer to the element in s1 where s2 begins (points to s2 in s1).
On error (if s2 does not occur in s1), strstr returns null.

Example:

#include <stdio.h>
#include <string.h>

int main(void)
{
   char *str1 = "IndiaBIX", *str2 = "ia", *ptr;

   ptr = strstr(str1, str2);
   printf("The substring is: %s\n", ptr);
   return 0;
}

Output: The substring is: iaBIX

The library function used to find the last occurrence of a character in a string is

A.	strnstr()
B.	laststr()
C.	strrchr()
D.	strstr()

Answer: Option C

Explanation:

Declaration: char *strrchr(const char *s, int c);

It scans a string s in the reverse direction, looking for a specific character c.

Example:

#include <string.h>
#include <stdio.h>

int main(void)
{
   char text[] = "I learn through IndiaBIX.com";
   char *ptr, c = 'i';

   ptr = strrchr(text, c);
   if (ptr)
      printf("The position of '%c' is: %d\n", c, ptr-text);
   else
      printf("The character was not found\n");
   return 0;
}

Output:

The position of 'i' is: 19

How will you print \n on the screen?

A.	printf("\n");
B.	echo "\\n";
C.	printf('\n');
D.	printf("\\n");

Answer: Option D

Explanation:

The statement printf("\\n"); prints '\n' on the screen.

If the two strings are identical, then strcmp() function returns

A.	-1
B.	1
C.	0
D.	Yes

Answer: Option C

Explanation:

Declaration: strcmp(const char *s1, const char*s2);

The strcmp return an int value that is

if s1 < s2 returns a value < 0

if s1 == s2 returns 0

if s1 > s2 returns a value > 0

Which of the following function sets first n characters of a string to a given character?

A.	strinit()
B.	strnset()
C.	strset()
D.	strcset()

Answer: Option B

Explanation:

Declaration:

char *strnset(char *s, int ch, size_t n); Sets the first n characters of s to ch

#include <stdio.h>
#include <string.h>

int main(void)
{
   char *string = "abcdefghijklmnopqrstuvwxyz";
   char letter = 'x';

   printf("string before strnset: %s\n", string);
   strnset(string, letter, 13);
   printf("string after  strnset: %s\n", string);

   return 0;
}

Output:

string before strnset: abcdefghijklmnopqrstuvwxyz

string after strnset: xxxxxxxxxxxxxnopqrstuvwxyz

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