Strings in Functional Programming

The string is defined as the group of the characters, which includes the space. The string is known as the one-dimensional character array. The string always ended by the “” or the NULL character. String is known as the predefined class. Most of the programming languages like C, C++, Erlang, Java supports String.

The below table shows how the string “Java” will look in memory.

Creating a string in C++

The below program will show how to create the string in C++. C++ is known as the object-oriented programming language.

  #include <iostream>   using namespace std;     int main () {         char season [20] = {‘H’, ‘o’, ‘l’, ‘i’, ‘d’, ‘a’, ‘y’, ‘�’};      cout << “Today is: “;      cout << season << endl;      return 0;   }   

The output of the above program is shown below:

Today is: Holiday

String in Erlang

The below code shows the creation of the string in Erlang. Erlang is known as the functional programming language.

  -module(HELLO).    -export([start/0]).     start() ->      St = “Today is: Independence”,       io:fwrite(“~p~n”,[St]).  

The output of the above program is just like, as shown below:

"Today is Independence"

String operations in C++

Different languages support different methods in the strings. The below table shows the predefined string methods supported by the C++ are:

Sr.No.	Methods and Description
1	Strcpy(t1,t2) It copies the string t2 into string t1
2	Strcat(t1,t2) It adds the string t2 at the end of t1
3	Strlen(t1) It provides the length of the string t1
4	Strcmp(t1,t2) It returns 0 when string t1 & t2 are the same
5	Strchr(t1,ch) It returns a pointer to the first occurrence of character ch in string t1
6	Strstr(t1,t2) It returns a pointer to the first occurrence of string t2 in string t1

The below program shows how we can use the above methods in C++

  #include <iostream>   #include <cstring>   using namespace std;     int main () {        char st1[20] = “Today is “;      char st2[20] = “Rakshabandhan”;      char st3[20];      int  length ;       strcpy( st3, st1); // here copy the s3 to s1      cout << “strcpy( st3, st1) : ” << st3 << endl;         strcat( st1, st2); // here concatenate st1 and st2      cout << “strcat( st1, st2): ” << st1 << endl;         len = strlen(st1);  // Length of the String after concatenation      cout << “strlen(st1) : ” << length << endl;      return 0;   }  

Output of the above program will look like as shown below:

strcpy(st3, st1)   :  Today is   strcat(st1, st2)   :  Today is Rakshabandhan   strlen(st1)         :  19

String operations in Erlang

String operations in Erlang are as shown below:

S.No.	Method & Description
1	len(l1) len(l1) method will return the characters present in the string.
2	equal(l1,l2) equal(l1,l2) will compare the two strings and return the result as true when the strings are equal else this will return the false.
3	concat(l1,l2) concat(l1,l2) method is used to add the string l2 at the end of the string l1.
4	str(l1,ch) str(l1,ch) method return the position of the character ch present in the string l1.
5	str (l1,l2) str(l1,l2) method returns the index position of l2 in string l1
6	substr(l1,l2,num) substr(l1,l2,num) method returns the string l2 from the string l1 which is based on the starting position & number of characters in the starting position
7	to_lower(l1) to_lower(l1) method returns string in lower case

Below program shows how we can use the above methods in Erlang.

  -module(HELLO).    -import(string,[concat/2]).    -export([start/0]).       start() ->       T1 = “Today is “,       T2 = “Tuesday”,       T3 = concat(T1,T2),       io:fwrite(“~p~n”,[T3]).  

Output of the above program will look like as shown below:

"Today is Monday"

Next Topic#

Strings in Functional Programming

Strings in Functional Programming

Creating a string in C++

String in Erlang

String operations in C++

String operations in Erlang

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