#include <iostream>
#include <string>
#include <sstream>
using namespace std;
using std::cout; 
using std::endl;
using std::string;

unsigned int digit_to_decimal(char digit) {
    // TODO(student): implement
	  int numd;
	  //std::cin >> digit;
	  //std::cout << digit << std::endl;
	
	  if ((digit >= '0' && digit <= '9')) {
	  	numd = digit - 48;
		  std::cout << numd;
		  return numd;
	  } else {
		  throw std::invalid_argument("input is not a valid digit");
	  }
}


char decimal_to_digit(unsigned int decimal) {
    // TODO(student): implement
	if (decimal > 9) {
		throw std::invalid_argument("input is not a valid digit");
	
	} else {
		char i_to_char = decimal + '0';
		std::cout << i_to_char;
		return i_to_char;
	}
}

string trim_leading_zeros(string num) {
    // TODO(student): implement
  
  //counts the index of trailing zeros
  int i = 0;
  char neg_sign = '-';
  string temp_str = num;
  cout << num;
  while(num[i] == '0') {
  i++;
  }
  
  //erase function removes trailing zeros of string
  //num.erase(0,i);
  //num.erase(0, min(num.find_first_not_of('0'), num.size()-1));
  //if (num[0] == '-') {
    ///temp_str = num.erase(0);
    //std::cout << temp_str;
    //temp_str = temp_str.erase(0, min(temp_str.find_first_not_of('0'), temp_str.size()-1));
    //temp_str = neg_sign + temp_str;
    //return temp_str;
  }
  //return temp_str;

int main () {
	  //digit_to_decimal('9');
	  //decimal_to_digit(2);
	  trim_leading_zeros("-00000");
  return 0;
}

C++ Online Compiler

Write, Run & Share C++ code online using OneCompiler's C++ online compiler for free. It's one of the robust, feature-rich online compilers for C++ language, running on the latest version 17. Getting started with the OneCompiler's C++ compiler is simple and pretty fast. The editor shows sample boilerplate code when you choose language as C++ and start coding!

Read inputs from stdin

OneCompiler's C++ online compiler supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample program which takes name as input and print your name with hello.

#include <iostream>
#include <string>
using namespace std;

int main() 
{
    string name;
    cout << "Enter name:";
    getline (cin, name);
    cout << "Hello " << name;
    return 0;
}

About C++

C++ is a widely used middle-level programming language.

  • Supports different platforms like Windows, various Linux flavours, MacOS etc
  • C++ supports OOPS concepts like Inheritance, Polymorphism, Encapsulation and Abstraction.
  • Case-sensitive
  • C++ is a compiler based language
  • C++ supports structured programming language
  • C++ provides alot of inbuilt functions and also supports dynamic memory allocation.
  • Like C, C++ also allows you to play with memory using Pointers.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition If-Else is used.

if(conditional-expression) {
   //code
}
else {
   //code
}

You can also use if-else for nested Ifs and If-Else-If ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to If-Else-If ladder.

switch(conditional-expression){    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
......    
    
default:     
 code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  //code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while (condition) {  
// code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {  
 // code 
} while (condition);

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity. Function gets run only when it is called.

How to declare a Function:

return_type function_name(parameters);

How to call a Function:

function_name (parameters)

How to define a Function:

return_type function_name(parameters) {  
 // code
}