So, I'm having a really dumb moment and I cant seem to remember how an if statement works, with only the variable name as the condition.. :(
Code:if(var){
//then do something
}
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So, I'm having a really dumb moment and I cant seem to remember how an if statement works, with only the variable name as the condition.. :(
Code:if(var){
//then do something
}
var evaluates to true for every nonzero value, zero is false
Kurt
So I suggest you experiment. Create a program and implement your variable and the if statement, compile and run the program. Determine if the program is doing what you expected. If that doesn't help then I suggest you find a good book or tutorial, if you can't figure out this you probably won't be able to understand most of the rest of the language.
Jim
Exploratory programming has its place, but it's rather a dangerous technique with C. A lot of C constructs are "undefined behaviour", which often means "it seems to work as you would hope, until such time as it doesn't".Quote:
Originally Posted by jimblumberg
Maybe with advanced topics, but I totally disagree when talking about such a basic issue. But the best option is to obtain a good book, read it, and enter and run all the sample programs.Quote:
Exploratory programming has its place, but it's rather a dangerous technique with C.
Jim
It is as this: Every expression, ( a = b + c ) , results or returns the lvalue of the expression. In this case, it would result to a.
So...
Anyone feel free to correct me.Code:if( a )
// a is not an expression, so it is evaluated as is. If a is a non-zero value, it results in a true condition
if( ( a = b + c ) )
// here we have an expression. The expression is evaluated; b is added to c and assigned to a. Then the lvalue, a, is examined
// to determine if it's a non-zero value. If it is a zero, it would be a false condition and the statement(s) inside the if statement won't be executed.
A few more comparison operators exist. GL.Code:if(dog == cats)
{
//code here
}
Consider yourself corrected.Quote:
Originally Posted by jwroblewski44
First I'll quote the definition of an expression from the 1999 ISO C standard, Section 6.5, para 1. "An expression is a sequence of operators and operands that specifies computation of a value, or that designates an object of a function, or that generates side effects, or that performs a combination thereof."
I haven't checked, but doubt the definition in C11 would differ substantially.
From this, in "if (a)", a is an expression, in the sense of being a sequence (of one operand and no operators) that retrieves the value of a. Retrieving the value of a variable is an example of a computation of a value.