List and explain string manipulation functions

Q29. List and explain string manipulation functions.

Answer: 

String Manipulation Functions

C++ provides a set of string handling functions to work on strings. These functions are available in string.h header files. The following are few string manipulation functions. They are,

1. strlen() function
2. strcpy() function
3. strcat() function
4. strcmp() function
5. strchr() function
6. strstr() function
7. substr() function

1. strlen() function

strlen() function returns the length of the string. It does not include the null terminator.

Syntax

strlen(string1);

Example

strlen(“Hello”);

2. strcpy() Function

strcpy() function is used to copy a string to a string variable.

Syntax

strcpy(string1, string2);

Example

            strcpy(name, “helloworld”);

Here, both string1 and string2 are character arrays where, string2 may be a string variable (or) string constant.

3 strcat() Function

strcat() function appends one string at the end of another string. It returns a single string that consists of characters of string1 followed by string2.

Syntax

strcat(string1, string2);

Example

strcat(“Hello”, “World”); 

4. strcmp() Function

strcmp( ) function is used to compare two strings. It returns 0 if string1 and string2 are equal, If string1 is greater than string2 it returns negative number and if string2 is less than string 1, it returns positive number.

Syntax

strcmp(string1, string2);

Example:

strcmp(‘“Hello”, “Help”);

5. strchr() Function

strchr( ) function finds the first occurrence of given character in a string.

Syntax

char strchr(const char str, int ch);

Example

strchr(welcome, e);

6. strstr() Function

strstr() function returns a pointer to first occurrence of string2 in string1.

Syntax

strstr(string1, string2);

Example

strstr(“estudies”, “foryou”);

7. substr() Function

substr( ) extracts the characters between two specified indices from a string and returns the new sub string.

Syntax

str.substr(start, end);

Example

str = “Hello world”

str.substr(2, 5);

Program

#include<iostream>

#include<cstring>

using namespace std;

int main( )

{

int x, lenl, len2;

char str1[] = “siagroup”;

char str2[] = “group”;

cout<<“\nstrlen( )”;

len1= strlen(str1);

len2= strlen(str2);

cout <<“\nstr1:”<<strl<< “\nlength <<lenl<<“characters”<< endl;

cout <<“\nstr2: ”<<str2<<“\nlength: »<<len2<<“characters”<<endl;

cout<<“\nstrcmp()”;

x= strcmp(str1, str2);

if(x!=0)

{

cout<<“\n\nStrings are not equal \n”;

cout<<“\nstrstr()”;

char *p = strstr(str1,str2);

if (p)

cout<< “\n” <<str2 <<“ is present in ” <<strl <<“ at position” <<p-str1;

else

cout<<“\n” <<str2<<“ is not present ” <<str1<<endl;

cout<<“\nstrcat()”;

strcat(str1, str2);

cout<<“\nstr1 =\t ’<<str1; /*joining strl and str2*/

}

else

cout<<“\n\nStrings are equal \n”;

char* ch = strchr(str1,'i’);

cout<<“\n strchr()”;

cout<<“\n’<<ch - str1+1;

strcpy(str1, str2);

cout<<“\nstrcpy( )”;

cout<<“\nstr1 = \t’<< str1;

return 0;

}

Output