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In this noncompliant code example, an assignment expression is the outermost expression in an if statement.

if (a = b) {
  /* ... */
}

While the intent of the code may be to assign b to a and test the value of the result for equality to zero, it is very frequently a case of the programmer mistakenly using the assignment operator = instead of the equals operator ==. Consequently, many compilers will warn about this condition making this coding error detectable by adhering to recommendation MSC00-C. Compile cleanly at high warning levels.

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When the assignment of b to a is not intended, this conditional block is now executed when a is equal to b.

if (a == b) {
  /* ... */
}

When the assignment is, if fact, intended, this is an alternative compliant solution:

if ((a = b) != 0) {
  /* ... */
}

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