This topic is about Solidity – While Loop.
The most basic loop in Solidity is the while loop which would be discussed in this chapter. The purpose of a while loop is to execute a statement or code block repeatedly as long as an expression is true. Once the expression becomes false, the loop terminates.
Flow Chart
The flow chart of while loop looks as follows −
Syntax
The syntax of while loop in Solidity is as follows −
while (expression) {
Statement(s) to be executed if expression is true
}
Example
Try the following example to implement while loop.
pragma solidity ^0.5.0;
contract SolidityTest {
uint storedData;
constructor() public{
storedData = 10;
}
function getResult() public view returns(string memory){
uint a = 10;
uint b = 2;
uint result = a + b;
return integerToString(result);
}
function integerToString(uint _i) internal pure
returns (string memory) {
if (_i == 0) {
return "0";
}
uint j = _i;
uint len;
while (j != 0) {
len++;
j /= 10;
}
bytes memory bstr = new bytes(len);
uint k = len - 1;
while (_i != 0) { // while loop
bstr[k--] = byte(uint8(48 + _i % 10));
_i /= 10;
}
return string(bstr);
}
}
Run the above program using steps provided in Solidity First Application chapter.
Output
0: string: 12
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