915
Example 1:
The following Java example contains a function to compute an average but does not validate that
the input value used as the denominator is not zero. This will create an exception for attempting
to divide by zero. If this error is not handled by Java exception handling, unexpected results can
occur.
Example Language: Java (Bad)
public int computeAverageResponseTime (int totalTime, int numRequests) {
return totalTime / numRequests;
}
By validating the input value used as the denominator the following code will ensure that a divide
by zero error will not cause unexpected results. The following Java code example will validate the
input value, output an error message, and throw an exception.
Example Language: (Good)
public int computeAverageResponseTime (int totalTime, int numRequests) throws ArithmeticException {
if (numRequests == 0) {
System.out.println("Division by zero attempted!");
throw ArithmeticException;
}
return totalTime / numRequests;
}
Example 2:
The following C/C++ example contains a function that divides two numeric values without verifying
that the input value used as the denominator is not zero. This will create an error for attempting
to divide by zero, if this error is not caught by the error handling capabilities of the language,
unexpected results can occur.
Example Language: C (Bad)
double divide(double x, double y){
return x/y;
}
By validating the input value used as the denominator the following code will ensure that a divide
by zero error will not cause unexpected results. If the method is called and a zero is passed as the
second argument a DivideByZero error will be thrown and should be caught by the calling block
with an output message indicating the error.
Example Language: (Good)
const int DivideByZero = 10;
double divide(double x, double y){
if ( 0 == y ){
throw DivideByZero;
}
return x/y;
}
...
try{
divide(10, 0);
}
catch( int i ){
if(i==DivideByZero) {
cerr<<"Divide by zero error";
}
}
CWE Version 4.14
CWE-369: Divide By Zero
CWE-369: Divide By Zero