String

A string is a sequence of characters, typically used to represent text. It could include letters, numbers, symbols, and whitespace. Strings are enclosed in single quotes (' ') or double quotes (" "). They're fundamental data types and are used extensively in almost every programming language.

Several things that can be done with strings include:

1. Manipulation
2. Concatenation
3. Slicing

String Manipulation

1. Finding a character with a particular index

• Strings are indexed, meaning each character has a position. Finding a character involves specifying its position (index) within the string.
• Pseudocode:

FUNCTION findCharacterAtIndex(inputString, index):
    IF index < 0 OR index >= length(inputString):
        RETURN "Index out of bounds"
    END IF
    
    characterAtIndex = inputString[index]
    RETURN characterAtIndex
END FUNCTION

• Example

C

char my_string[] = "Hello, World!";
char char_at_index = my_string[7];
printf("%c\n", char_at_index);

C++

int num = 42;
string my_string = "Hello, World!";
char char_at_index = my_string[7];
cout << char_at_index << endl;

Java

String myString = "Hello, World!";
char charAtIndex = myString.charAt(7);
System.out.println(charAtIndex);

Python

my_string = "Hello, World!"
char_at_index = my_string[7]
print(char_at_index)

2. Changing all characters to lowercase

• This operation converts all characters in a string to lowercase.

C

char myString[] = "Hello, World!";
int length = strlen(myString); 
for (int i = 0; i < length; i++) {
    if (myString[i] >= 'A' && myString[i] <= 'Z') {
        myString[i] = myString[i] + 32; // converting uppercase to lowercase in ASCII
    }
}
printf("%s\n", myString);

C++

string myString = "Hello, World!";
for (int i = 0; i < myString.length(); i++) {
    myString[i] = tolower(myString[i]); // using tolower function
}
cout << myString << endl;

Java

String myString = "Hello, World!";
String lowercaseString = myString.toLowerCase();
System.out.println(lowercaseString);

Python

my_string = "Hello, World!"
lowercase_string = my_string.lower()
print(lowercase_string)

3. Changing all characters to uppercase

• This operation converts all characters in a string to uppercase.

C

char myString[] = "Hello, World!";
int length = strlen(myString);
for (int i = 0; i < length; i++) {
    if (myString[i] >= 'a' && myString[i] <= 'z') {
        myString[i] = myString[i] - 32; // converting lowercase to uppercase in ASCII
    }
}
printf("%s\n", myString);

C++

string myString = "Hello, World!";
for (int i = 0; i < myString.length(); i++) {
    myString[i] = toupper(myString[i]); // using toupper function
}
cout << myString << endl;

Java

String myString = "Hello, World!";
String uppercaseString = myString.toUpperCase();
System.out.println(uppercaseString);

Python

my_string = "Hello, World!"
uppercase_string = my_string.upper()
print(uppercase_string)

Concat String

Concatenation is like string addition. It joins multiple strings end-to-end to form a single longer string.

C

char string1[] = "Hello, ";
char string2[] = "World!";
char concatenatedString[50];

strcpy(concatenatedString, string1);
strcat(concatenatedString, string2);

printf("%s\n", concatenatedString);

C++

string string1 = "Hello, ";
string string2 = "World!";
string concatenatedString = string1 + string2;

cout << concatenatedString << endl;

Java

String string1 = "Hello, ";
String string2 = "World!";
String concatenatedString = string1.concat(string2);

System.out.println(concatenatedString);

Python

string1 = "Hello, "
string2 = "World!"
concatenated_string = string1 + string2
print(concatenated_string)

• Pseudocode

FUNCTION concatenateStrings(string1, string2):
    concatenatedString = string1 + string2
    RETURN concatenatedString

Slice String

String slicing extracts a part of a string by specifying the starting and ending indices or positions.

C

char inputString[] = "Hello, World!";
int startIndex = 3;
int endIndex = 8;
char slicedString[50];

strncpy(slicedString, inputString + startIndex, endIndex - startIndex);
slicedString[endIndex - startIndex] = '\0';
printf("%s\n", slicedString);

C++

string inputString = "Hello, World!";
int startIndex = 3;
int endIndex = 8;
string slicedString = inputString.substr(startIndex, endIndex - startIndex);
cout << slicedString << endl;

Java

String inputString = "Hello, World!";
int startIndex = 3;
int endIndex = 8;
String slicedString = inputString.substring(startIndex, endIndex);
System.out.println(slicedString);

Python

input_string = "Hello, World!"
start_index = 3
end_index = 8
sliced_string = input_string[start_index:end_index]
print(sliced_string)

• Pseudocode

FUNCTION sliceString(inputString, startIndex, endIndex):
    slicedString = inputString[startIndex:endIndex]
    RETURN slicedString