The values are comes from xml, user only declare what condition to do.
string condition ="25<10";
Now, I want to use this in if condition like:
if(condition)
{
//my condition
}
and I am getting this error
Cannot implicitly convert type string to bool
Can anyone tell me how to do this?
If provided conditions are not that complex, you can try an old trick with DataTable:
https://msdn.microsoft.com/en-us/library/system.data.datatable.compute(v=vs.110).aspx
private static bool ComputeCondition(string value) {
using (DataTable dt = new DataTable()) {
return (bool)(dt.Compute(value, null));
}
}
...
string condition ="25<10";
if (ComputeCondition(condition)) {
//my condition
}
<> insted of !=First of all:
If you do this string condition ="25<10"condition will have the value 25<10 and not true or flase! If 25, 10 and the < come from your xml paste them into 3 different string like x, y and z and compare them like:
string input = "25<10"; //input form your xml
int operatorPosition;
//get the position of the operator
if(input.contains("<")){
operatorPosition = input.IndexOf("<");
}else{
operatorPosition = input.IndexOf(">");
}
//maybe i messed up some -1 or +1 here but this should work this
string x = input.Substring(0,operatorPosition-1);
string y = input.Substring(operatorPosition+1, input.length-1);
string z = input.charAt(operatorPosition);
//check if it is < or >
if(z.equals("<"){
//compare x and y with <
if(Int32.parse(x) < Int32.parse(y)){
//do something
}else{
//do something
}
}
//z does not equal < so it have to be > (if you dont have something like = otherwise you need to check this too)
else{
if(Int32.parse(x) < Int32.parse(y)){
//do something
}else{
//do something
}
Maybe there is a better way to transform a pure string input into a if clause but this is the way i would go.
x = "25 < 10". This requires Contains method to determine less-than operator & String.Split to get 2 operands, then you can compare them in if-condition.
You can use this code for do it:
string statment = "10<25"; // Sample statement
string leftOperand = statment.Split('<').First();
string rightOperand = statment.Split('<').Last();
int relationValue = Math.Sign(leftOperand.CompareTo(rightOperand));
if(relationValue == -1)
{
// leftOperand < rightOperand
}
else if (relationValue == 0)
{
// leftOperand == rightOperand
}
else if (relationValue == 1)
{
// leftOperand > rightOperand
}
If you just want check leftOperand < rightOperand you can use ternary operator like this:
bool condition = Math.Sign(leftOperand.CompareTo(rightOperand)) == -1 ? true : false;
condition ? first_expression : second_expression; i guess but it's still an if condition just in the short version
leftOperand < rightOperand)?leftOperand < rightOperand without if. Please see this.
if (25 < 10)is valid, butif ("25 < 10")is not valid).