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strtol() function in C++ STL

Last Updated : 1 Jun, 2022

The strtol() function is a builtin function in C++ STL which converts the contents of a string as an integral number of the specified base and return its value as a long int. Syntax:

strtol(s, &end, b)

Parameters: The function accepts three mandatory parameters which are described as below:

  • s: specifies the string which has the representation of an integral number.
  • end: indicates where the conversion stopped, refers to an already allocated object of type char*. The value of the end is set by the function to the next character in s after the last valid character.It can also be a null pointer, in which case it is not used.
  • b: specifies to the base of the integral value.

Return Value: The function returns value of two types:

  • If a valid conversion occurs, then a long int value is returned.
  • If no valid conversion happens, then 0 is returned.

Below programs illustrate the above function. Program 1: 

Output:
Number in String = 6010IG_2016p
Number in Long Int = 6010
End String = IG_2016p

Number in String = 47
Number in Long Int = 47
Null pointer

Program 2: 

Output:
489bc to Long Int with base-4 = 0
End String = 489bc
123s to Long Int with base-11 = 146
End String = s
56xyz to Long Int with base-36 = 8722043

Program 3: 

Output:
312gfg to Long Int with base-0 = 312
End String = gfg

0q15axtz to Long Int with base-0 = 0
End String = q15axtz

33ffn to Long Int with base-0 = 33
End String =

Program 4 

Output:
22abcd to Long Int with base-6 = 14
End String = abcd

114cd to Long Int with base-2 = 3
End String = 4cd

e10.79 to Long Int with base-10 = 0
End String = e10.79
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