Different ways to convert String to number in Perl with code examples

Different ways to convert String to number in Perl with code examples

This tutorial explains multiple ways to convert a String to a Number in Perl with Code examples.

  • Use String variable by append with a number o using the + operator.For example, "123"+0 returns number 123.
  • use the Int type constructor. For example, int("111") returns 111
  • sprintf function, Assign the result sprintf("%d", "98"); and variable holds number 98

How to Convert String to Number in Perl?

  • using string append with + Symbol The string contains a group of characters and letters, enclosed in double or single quotes in Perl. A number contains a numeric value.

For example, if the string contains numbers, Append with zero to return the number.

my $str = "123";
print $str + 0,"\n";

Output:

123

If the string contains mixed letters and numbers, letters are after numbers, It returns a number. Perl always processes the statements from left to right and Since It is a context-based programming language, it understands addition context as implicit and string is converted to zero, 999asd returns 999+0, appending explicit again with the + operator with 0 being the same number.

my $str = "999asd";
print $str + 0,"\n";

Output:

999

if the string contains letters before numbers, It treats it as a string, Converting string to a number is zero.

my $str = "asd999";
print $str + 0,"\n";

Output:

0

Please note with this approach, if the number starts with INF and nan, it always returns the same string as given below

my $str = "inf199";
print $str + 0,"\n";
my $str = "nan199";
print $str + 0,"\n";

Output:

inf
NaN

if the string contains letters in between numbers, it always returns the first number.


my $str = "1a99";
print $str + 0,"\n";

Output:

1
  • using int type constructor The second way, Using the int constructor, passes the string parameter to Int, and It casts to a number.

Here is a cast string to number using an int example

my $str = "456";
$number = int($str);
print $number,"\n"; # 456

my $str1 = "456abc";
$number1 = int($str1);
print $number1,"\n";# 456

my $str2 = "abc";
$number2 = int($str2);
print $number2;# 0

Output

456
456
0
  • use sprintf function

sprintf is a built-in function in Perl. It contains the first argument as a formatter and the second is a variable value. It converts a second value into a given format(first argument).

Here is a sprintf function in Perl to convert a string to a number.

my $str1 = "456";
$number1 = sprintf("%d", $str1);

print $number1,"\n"; # 456

my $str2 = "456abc";
$number2 = sprintf("%d", $str2);

print $number2,"\n"; # 456

my $str3 = "abc";
$number3 = sprintf("%d", $str3);
print $number3,"\n"; # 0

Conclusion

Since Perl does not do the automatic conversion from String to Number, So you have to manually do the conversion using different methods.