The University of Iowa
The College of Liberal Arts and Sciences
Department of Computer Science
Lecture/Lab #5
auto, understanding compilation errors, arithmetic
What type would you use...
to represent a boolean value?
to represent an integer?
to indicate that a function doesn't return anything?
for floating-point computations?
to store the value of a single character?
What operator gives us the size of a type in bytes?
to store a string?
#include <iostream>
#include <cmath> // for std::sqrt
int main()
{
auto b = true; // a bool
auto ch = 'x'; // a char
auto i = 123; // an int
auto d = 1.2; // a double
auto z = std::sqrt(d); // z has the type of whatever
// sqrt(y) returns
auto bb{true}; // bb is a bool
}
We don’t need to state the type explicitly when it can be deduced from the initializer:
Recommendation: use auto by default, unless you have a specific reason to mention the type explicitly.
Use `auto` to simplify function and variable declarations where it makes sense (without changing the meaning of the program)
Open the exercise template
Write your code, press Run to test
When you're done, grab your Repl's link and send it as a direct message to me (agurtovoy)
Click on the corresponding option in the "Lab5 exercises" poll in #general
General error message format:
source.cpp:<line number>:<column>: <error message>
Common error categories:
Syntax errors: missing/unnecessary semicolon, mismatching parentheses/brackets, unterminated string literal and other instances of incorrect language grammar
Semantic errors: undeclared identifier, missing return statement, mismatching types/number of function arguments and other type system-related and logical errors that can be caught at compile time
Link-time errors: missing function or variable definitions
Always start with the very first error
Fix the program's compilation errors while using your best judgement to preserve the intent of the program
Open the exercise template
Write your code, press Run to test
When you're done, grab your Repl's link and send it as a direct message to me (agurtovoy)
Click on the corresponding option in the "Lab5 exercises" poll in #general
Arithmetic operators
x + y // plus
+x // unary plus
x − y // minus
−x // unary minus
x * y // multiply
x / y // divide
x % y // remainder (modulus),
// ints onlyComparison operators
x == y // equal
x != y // not equal
x < y // less than
x > y // greater than
x <= y // less than or equal
x >= y // greater than
// or equalLogical operators
x && y // logical and
x || y // logical or
!x // logical not
// (negation)Bitwise operators (ints only)
x & y // bitwise and
x | y // bitwise or
x ^ y // bitwise xor
~x // bitwise complement
x << y // left shift
x >> y // right shift