COP3014 Strings

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

0: 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

What will be the output of the program ? #include<stdio.h> #include<string.h> int main() { char str[] = "India\0\BIX\0"; printf("%s\n", str); return 0; }

A string is a collection of characters terminated by '\0'. Step 1: char str[] = "India\0\BIX\0"; The variable str is declared as an array of characters and initialized with value "India" Step 2: printf("%s\n", str); It prints the value of the str. The output of the program is "India".

What is the output: #include <stdio.h> #include <string.h> int main(int argc, char* argv[]) { // -------------------------------- // strcat (destination, source) // appends source to destination. destination has to be large enough to contain the length of source including the null character. // -------------------------------- char str1[32] = "I love programming "; char str2[32] = "C on Linux"; char str3[32] = "I love programming "; char str4[32] = "C on Linux"; strcat(str1, str2); printf("After strcat, str1 = %s\n", str1); printf("Length of str1 = %ld\n", strlen(str1)); strcat(str4, str3); printf("After strcat, str1 = %s\n", str4); printf("Length of str1 = %ld\n", strlen(str4)); return 0; }

After strcat, str1 = I love programming C on Linux Length of str1 = 29 After strcat, str1 = C on LinuxI love programming Length of str1 = 29

#include <string.h> #include <stdio.h> int main(void) { // -------------------------------- // strncpy (destination, source, n) // copies n characters from source to destination. if n < strlen(destination) the rest of destination is left intact and only the first n chars get overwritten by the first n chars of source. // -------------------------------- char str1[] = "I love programming "; char str2[] = "C on Linux"; strncpy(str2, str1, 3); printf("After strncpy, str2 = %s\n", str2); }

After strncpy, str2 = I ln Linux

what is the output: #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; }

Enter a string: IndiaBIX The string input was: IndiaBIX

#include <string.h> #include <stdio.h> int main(void) { // -------------------------------- // strtok (str, delim) // returns a substring of str from its beginning to the first delimiter // -------------------------------- char str1[] = "I lo:ve linux"; printf("%s\n", strtok(str1, ":")); return 0; }

I lo

what is the output: #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; }

Length = 8

what is the output: #include <string.h> #include <stdio.h> int main(void) { // -------------------------------- // strcpy (destination, source) // copies the source to the destination. the destination has to be large enough to contain the source along with the null terminator // -------------------------------- char str1[] = "I love programming "; char str2[] = "C on Linux"; printf("Length of str1 before strcpy = %ld\n", strlen(str1)); strcpy(str1, str2); printf("After strcpy, str1 = %s\n", str1); printf("Length of str1 after strcpy = %ld\n", strlen(str1)); return 0; }

Length of str1 before strcpy = 19 After strcpy, str1 = C on Linux Length of str1 after strcpy = 10

What is the output: #include <stdio.h> #include <string.h> int main(int argc, char* argv[]) { // -------------------------------- // size_t strlen (string) // computes the length of the string str up to, but not including the null terminator '\0'. // -------------------------------- char str1[32] = "I love programming "; char str2[32] = "C on Linux"; printf("My first string is : %s\n", str1); printf("My second string is : %s\n", str2); printf("str1 is %ld characters long\n", strlen(str1)); printf("str2 is %ld characters long\n", strlen(str2)); return 0; }

My first string is : I love programming My second string is : C on Linux str1 is 19 characters long str2 is 10 characters long Once one of them gets executed, the others do not matter.

What is the output of the program: #include<stdio.h> int main() { char p[] = "%d\n"; p[1] = 'c'; printf(p, 65); return 0; }

Step 1: char p[] = "%d\n"; The variable p is declared as an array of characters and initialized with string "%d". Step 2: p[1] = 'c'; Here, we overwrite the second element of array p by 'c'. So array p becomes "%c". Step 3: printf(p, 65); becomes printf("%c", 65); Therefore it prints the ASCII value of 65. The output is 'A'.

what is the output: #include<stdio.h> #include<string.h> int main() { char str1[20] = "Hello", str2[20] = " World"; printf("%s\n", strcpy(str2, strcat(str1, str2))); return 0; }

Step 1: char str1[20] = "Hello", str2[20] = " World"; The variable str1 and str2 is declared as an array of characters and initialized with value "Hello" and " World" respectively. Step 2: printf("%s\n", strcpy(str2, strcat(str1, str2))); => strcat(str1, str2)) it append the string str2 to str1. The result will be stored in str1. Therefore str1 contains "Hello World". => strcpy(str2, "Hello World") it copies the "Hello World" to the variable str2. Hence it prints "Hello World".

what will be the output: #include<stdio.h> #include<string.h> int main() { printf("%d\n", strlen("123456")); return 0; }

The function strlen returns the number of characters in the given string. Therefore, strlen("123456") returns 6. Hence the output of the program is "6".

what is the output: #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; }

The position of 'i' is: 19

How will you print \n on the screen?

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

What is the output: #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; }

The substring is: iaBIX

Strings definition

are one-dimensional arrays of characters termianted by a null character'\0'.

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

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

different ways to declare c-strings:

char g[8] = {'s', 't', 'r', 'i', 'n', 'g', '\0\}; char g[8] = "string"; char g[8]="str"; char g[]="string";//similar to an array

a null-terminated string contains the ______that comprise the string followed by a ____.

characters that comprise the string followed by a null.

strcmp

compares one string to another

strncat

concatenates n characters of a string to another

strcat()

concatenates two strings; concatenates str2 at the end of str1

strcpy

copy a string to another

ctrncpy

copy the first n characters of a string to another

strstr

get the first occurence of a string in another

strlen

get the length of a string

strchr

get the location of the first occurrence of a character in a string.

strrchr

get the location of the last occurrence of a character in a string

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

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

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

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

strings are ____ terminated with the character '\0'

null terminated with the character '\0'

What will be the output: #include<stdio.h> int main() { printf(5+"Good Morning\n"); return 0; }

printf(5+"Good Morning\n"); It skips the 5 characters and prints the given string. Hence the output is "Morning"

strtok

split the string into tokens.

#include <string.h> #include <stdio.h> int main(void) { // -------------------------------- // strchr (str, char) // searches for the 1st occurence of char in str starting from the left. it returns the string // starting at that location to the end of the string // -------------------------------- char str1[] = "I love linux"; printf("strchr = %s\n", strchr(str1,'l')); return 0; }

strchr = love linux

In C, an array of characters is called a ___.

string

what is the output: #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; }

string before strnset: abcdefghijklmnopqrstuvwxyz string after strnset: xxxxxxxxxxxxxnopqrstuvwxyz

C provides a rich set of functions for ________.

string manipulation.

#include <string.h> #include <stdio.h> int main(void) { // -------------------------------- // strcasecmp (str1, str2) // compares str1 & str2 independent of case. if str1 == str2i (independent of case), the functions returns 0, otherwise it returns 1 // -------------------------------- char str1[] = "I love linux"; char str2[] = "I Love linux"; if (!strcasecmp(str1, str2)) printf("strings are the same\n"); return 0; }

strings are the same

#include <string.h> #include <stdio.h> int main(void) { // -------------------------------- // strrchr (str, char) // searches for the last occurence of char in str starting from the left (or the first occurence of the char if searching from the right).. // it returns the string starting at that location to the end of the string // -------------------------------- char str1[] = "I love linux"; printf("strrchr = %s\n", strrchr(str1, 'l')); return 0; }

strrchr = linux

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

strrchr() Explanation: Declaration: char *strrchr(const char *s, int c); It scans a string s in the reverse direction, looking for a specific character c.

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

strstr() 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.