http://stackoverflow.com/questions/376278/parameter-evaluation-order-before-a-function-calling-in-c http://stackoverflow.com/questions/376278/parameter-evaluati

http://stackoverflow.com/questions/376278/parameter-evaluation-order-before-a-function-calling-in-c http://stackoverflow.com/questions/376278/parameter-evaluati... https://www.securecoding.cert.org/confluence/display/seccode/EXP10-C.+Do+not+depend+on+the+order+of+evaluation+of+subexpressions+or+the+order+in+which+side+effects+take+place https://www.securecoding.cert.org/confluence/display/seccode... Basically, do not depend on the order of evaluation of arguments to a function call, because it is unspecified and left to the implementation to decide according to the C99 standard. EDIT: Another explanation, pertinent to your example can be found here - http://c-faq.com/expr/evalorder2.html http://c-faq.com/expr/evalorder2.html