atol() in C
The atol() function converts a C-style string (array of characters), passed as an argument to atol() function, to a long integer. It converts the C-string str to a value of type long int by interpreting the characters of the string as numerical values. It discards the leading whitespace characters until a non-whitespace character is found.
Syntax
long int atol ( const char * str );
Parameters
- The function accepts one mandatory parameter str which represents an integral number.
Return Value
- The function returns the long int representation of the string.
- It returns ‘0’ if no valid conversion can be performed.
Note: If the C-string str passed to atol() function is either empty or contains only whitespace characters, it is not a valid integral number, no conversion will be performed and it will return zero.
Example: Program to Illustrate the Working of atol() Function.
C
// C program to illustrate// working of atol() function.#include <stdio.h>// Include this header for atol function#include <stdlib.h>int main(){ // char array of numbers char str1[] = "5672345"; // Function calling to convert to a long int long int num1 = atol(str1); printf("Number is %ld\n", num1); // char array of numbers without spaces char str2[] = "10000002 0"; // Function calling to convert to a long int long int num2 = atol(str2); printf("Number is %ld\n", num2); return 0;} |
C++
// CPP program to illustrate// working of atol() function.#include <bits/stdc++.h>using namespace std;int main(){ // char array of numbers char str1[] = "5672345"; // Function calling to convert to a long int long int num1 = atol(str1); cout << "Number is " << num1 << "\n"; // char array of numbers of spaces char str2[] = "10000002 0"; // Function calling to convert to a long int long int num2 = atol(str2); cout << "Number is " << num2 << "\n"; return 0;} |
Number is 5672345 Number is 10000002
atol(), atoll() and atof() functions in C/C++
In C/C++, atol(), atoll(), and atof() are functions used to convert strings to numbers of different types. These functions are Standard Library functions. In this article, we will learn these String-to-number conversion functions in C/C++.