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Using the assignment operator in the outermost expression in a conditional expression of a selection statement (if or switch) or an iteration statement (while, do, or for) shall be diagnosed because this typically indicates programmer error and can result in unexpected behavior.

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

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

While this the intent of the code may be intendedindeed be to assign b to a and test the value of the result for equality to zero, it is almost always 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 . Consequently, making this coding error would typically be eliminated by adherence detectable by adhering to MSC00-C. Compile cleanly at high warning levels.

Compliant Solution

This 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) {
  /* ... */
}

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

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

It is less desirable in general, depending on what was intended, because it mixes the assignment in the condition, but it is clear that the programmer intended the assignment to occur.

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