Updated April 6, 2023
Introduction to TypeScript string to number
A string in TypeScript can be converted to a number using an operator called unary plus (+) operator or using the functions called parseInt function or parseFloat function, or Number function where the unary plus operator converts the numbers represented as a string, Boolean values represented by either true or false and null to numbers. Parseint function converts the given string into an integer, and parseFloat function converts the given string to a number. Number function is similar to the unary plus operator, and it converts the given string to a number, and all these functions return NaN if the given string cannot be converted to a number.
Syntax to declare unary plus(+) operator in TypeScript:
+"string_to_be_converted_to_number";Where string_to_be_converted_to_number is the string that is to be converted into a number.
Syntax to declare parseInt function in TypeScript:
parseInt(string_to_be_converted_to_number, radix);Where string_to_be_converted_to_number is the string that is to be converted into a number, and the value of radix is 2 for binary numbers, 8 for octal numbers, 10 for decimal numbers and 16 for hexadecimal numbers. The default value for radix is 16.
Syntax to declare parseFloat function in TypeScript:
parseFloat("string_to_be_converted_to_number");Where string_to_be_converted_to_number is the string that is to be converted into a number.
Syntax to declare Number function in TypeScript:
Number("string_to_be_converted_to_number");Where string_to_be_converted_to_number is the string that is to be converted into a number.
Steps to Convert string to number in TypeScript
- A string in TypeScript can be converted to a number using an operator called unary plus (+) operator or using the functions called parseInt function or parseFloat function or Number function.
- The unary plus operator converts the numbers represented as a string, boolean values represented by either true or false and null to numbers.
- The unary plus operator converts an empty string or null to number 0.
- The unary plus operator converts the boolean value true to 1 and the Boolean value false to 0.
- The unary plus operator converts the octal numbers or hexadecimal numbers to a decimal value.
- The unary plus operator also works on scientific notation numbers.
- The unary plus operator returns NaN or Not a Number in case it cannot convert the given string to a number.
- The parseInt function converts the given string into an integer.
- The parseInt function converts infinity, null, boolean values true and false, empty strings to NaN.
- The parseInt function treats the strings beginning with 0x as a hexadecimal number and do not recognize the octal number that begins with 0o.
- The parseFloat function converts the given string into an integer or a decimal number.
- The parseFloat function converts null, boolean values true and false, empty strings to NaN.
- The parseFloat function returns infinity if the given string is infinity.
- The parseFloat function returns 0 for the strings beginning with 0x and 0o and do not recognize hexadecimal or octal numbers.
- The number function converts the given string to a number.
- The number function converts the null or empty string to 0.
- The number function converts the boolean value true to 1 and the boolean value false to 0.
- The number function converts the hexadecimal numbers or octal numbers to decimal values.
- The number function also works on scientific notation numbers.
- The number function returns NaN or Not a Number in case it cannot convert the given string to a number.
Examples of TypeScript string to number
Given below are the examples of TypeScript string to number:
Example #1
TypeScript program to check if a given string is Not a Number or no using isNan() function and then convert the string to a number using the unary plus operator.
Code:
convert("0o100")
//defining a function to convert the given string to a number using unary plus operator
function convert(value)
{
//using isNaN function to check if the given string is a number or not
if (isNaN(+value))
{
console.log("The given value is Not a Number(NaN)")
}
else
{
console.log("The value after converting the given string to a number is:\n")
console.log(value)
}
}Output:
In the above program, we are defining a function to convert the given string into a number using unary plus operator within which we are also checking if the given string is a number or no, in case it is a number represented as a string, it is converted to a number.
Example #2
TypeScript program to check if a given string is Not a Number or no using isNan() function and then convert the string to a number using parseInt function.
Code:
convert("0o100")
//defining a function to convert the given string to a number using unary plus operator
function convert(value: any)
{
//using isNaN function to check if the given string is a number or not
if (isNaN(+value))
{
console.log("The given value is Not a Number(NaN)")
}
else
{
console.log("The value after converting the given string to a number is:")
console.log(parseInt(value))
}
}Output:
In the above program, we are defining a function to convert the given string into a number using parseInt function, within which we are also checking if the given string is a number or no, in case it is a number represented as a string, it is converted to a number.
Rules and Regulations
Given below are the rules and regulations for converting string to number in TypeScript:
- The unary plus operator converts the numbers represented as a string, boolean values represented by either true or false and null to numbers.
- The unary plus operator converts an empty string or null to number 0.
- The unary plus operator converts the boolean value true to 1 and the boolean value false to 0.
- The unary plus operator converts the octal numbers or hexadecimal numbers to a decimal value.
- The parseInt function converts infinity, null, boolean values true and false, empty strings to NaN.
- The parseInt function treats the strings beginning with 0x as a hexadecimal number and do not recognize the octal number that begins with 0o.
- The parseFloat function converts null, boolean values true and false, empty strings to NaN.
- The parseFloat function returns infinity if the given string is infinity.
- The parseFloat function returns 0 for the strings beginning with 0x and 0o and do not recognize hexadecimal or octal numbers.
- The number function converts the given string to a number.
- The number function converts the null or empty string to 0.
- The number function converts the boolean value true to 1 and the boolean value false to 0.
- The number function converts the hexadecimal numbers or octal numbers to decimal values.
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