V760. Two identical text blocks detected. The second block starts with NN string.


The analyzer detected a code fragment that may contain a typo. It is very likely that this code was written using the Copy-Paste technique. Warning V760 is triggered when the analyzer detects two identical text blocks following one another. This diagnostic basically relies on heuristics and, therefore, may produce false positives.

Consider the following example:

void Example(int *a, int *b, size_t n)
{
  ....
  for (size_t i = 0; i != n; i++)
    a[i] = 0;
  for (size_t i = 0; i != n; i++)
    a[i] = 0;
  ....
}

This code was written using the Copy-Paste technique, and the programmer forgot to change the array name in the second block. This is what the code was meant to look like:

void Example(int *a, int *b, size_t n)
{
  ....
  for (size_t i = 0; i != n; i++)
    a[i] = 0;
  for (size_t i = 0; i != n; i++)
    b[i] = 0;
  ....
}

This message is not generated for more than two identical blocks, for example:

void Foo();
void Example()
{
  ....
  Foo();
  Foo();
  Foo();
  Foo();
  ....
}

Sometimes the reason for generating the warning is not obvious. Consider this example:

switch(t) {
  case '!': InvokeMethod(&obj_Sylia, "!", 1); break; 
  case '~': InvokeMethod(&obj_Sylia, "~", 1); break; 
  case '+': InvokeMethod(&obj_Sylia, "+", 1); break;
  case '-': InvokeMethod(&obj_Sylia, "-", 1); break; 
    break;
  default:
    SCRIPT_ERROR(PARSE_ERROR); 
}

We need to take a closer look: in this example, we are dealing with very short repeated block, the 'break' statement. One of its instances is not necessary. This defect does not cause a real bug, but the extra 'break' should be removed:

switch(t) {
  case '!': InvokeMethod(&obj_Sylia, "!", 1); break; 
  case '~': InvokeMethod(&obj_Sylia, "~", 1); break; 
  case '+': InvokeMethod(&obj_Sylia, "+", 1); break;
  case '-': InvokeMethod(&obj_Sylia, "-", 1); break; 
  default:
    SCRIPT_ERROR(PARSE_ERROR); 
}

Note

Code duplication is not in itself an error. However, even when there is no real bug, the V760 warning can be treated as a hint that you should put identical code blocks in a function. See also diagnostic V761.

You can look at examples of errors detected by the V760 diagnostic.


Bugs Found

Checked Projects
346
Collected Errors
13 188