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# Case conversion of a String in R Language – toupper(), tolower(), casefold() and cartr() Function

• Last Updated : 26 May, 2020

toupper() function in R Language is used to convert the lowercase letters to uppercase.

Syntax: toupper(x)

Parameters:
x: character vector

Example:

 `# R program to illustrate ``# uppercase of  vectors `` ` `# Create example character string``x <``-` `"GeeksforGeeks"`                   `toupper(x)`` ` `print``(x)`

Output:

`GEEKSFORGEEKS`

Here in the above code we have converted a example vector of characters to uppercase characters.

#### tolower() Function

`tolower()` function is used to convert the uppercase letters to lowercase.

Syntax: tolower(x)

Parameters:
x: character vector

Example:

 `# R program to illustrate ``# uppercase of  vectors `` ` `# Create example character string``x <``-` `"GeeksforGeeks"` `tolower(x)`` ` `print``(x)`

Output:

`geeksforgeeks`

#### casefold() Function

`casefold()` function takes character vector and boolean value as argument. This boolean value decides the conversion to upper and lower case.

Syntax: casefold(x, upper)

Parameters:
x: Character Vector
upper: Boolean value for case conversion

Example 1:

 `# Create example character string``x <``-` `"GeeksforGeeks"`` ` `# Convert to lower case letters ``x <``-` `casefold(x, upper ``=` `FALSE)  `` ` `print``(x)            `

Output:

`"geeksforgeeks"`

Here in the above code, the boolean value for the upper is set to be FALSE to convert the character vector to lowercase.

Example 2:

 `# Create example character string``x <``-` `"GeeksforGeeks"`` ` `# Convert to upper case letters ``casefold(x, upper ``=` `TRUE)   `` ` `print``(x)              `

Output:

`"GEEKSFORGEEKS"`

Here in the above code, the boolean value for the upper is set to be TRUE to convert the character vector to Uppercase.

#### cartr() Function

`cartr()` function is used when we have to make some characters to upper case and some to lower case.

Syntax: cartr(x, old, new)

Parameters:
x: character vector
old: a character string specifying the characters to be translated.
new: a character string specifying the translations

Example:

 `# Create example character string``x <``-` `"GeeksforGeeks"`` ` `# Translate to upper and lower case``chartr(old ``=` `"Geeks"``, new ``=` `"GeEkS"``, x)    `

Output:

`"GeEkSforGeeks"`

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