This function searches the string "str" to identify a sub-string containing a parenthesised expression and returns the character positions of the opening and closing parentheses in the "f" and "l" arguments. Allowance is made for nested parentheses. If a parenthesised expression was not found, then the returned value of "f" will be greater than the returned value of "l".

void chrFparx( const char $\ast$str, char oppar, char clpar, size_t $\ast$f, size_t $\ast$l )

str

oppar

clpar

$\ast$f

$\ast$l