int main(void)
{
/*
* Function pointer declaration.
* int <- return value of the function
* (*arithmetic_operator) <- pointer to the function
* (int, int) <- arguments to the function
*
* Note that the function signature of the
* function pointer and the function pointed by
* the function pointer should be the same.
*
* e.g. signature of arithmetic_operator
* is same as addition, subtraction, multiplication
*/
int (*arithmetic_operator)(int, int);
float (*farithmetic_operator)(int, int);
/*
* This statement is like a normal pointer assignment.
*/
arithmetic_operator = &addition;
printf("%d\n", arithmetic_operator(10, 20));
arithmetic_operator = &subtraction;
printf("%d\n", arithmetic_operator(20, 10));
arithmetic_operator = &multiplication;
printf("%d\n", arithmetic_operator(10, 20));
/*
* What happens when the function signature of the function pointer
* and the assigned function does not match.
*
* Note: Warning is reported by the C compiler on the
* incompatible pointer assignment
*
* Why does the following printf statements print
* different values?
*/
printf("Non-matching function signatures\n");
arithmetic_operator = &division;
printf("%f\n", arithmetic_operator(10, 20));
printf("%f\n", division(10, 20));
printf("\nMatching function signatures\n");
farithmetic_operator = &division;
printf("%f\n", farithmetic_operator(10, 20));
printf("%f\n", division(10, 20));
return 0;
}
//main function
int main()
{
initialize_Symbol_Table();
remove("a4_1.out");
char input[1000];
token t;
int i;
//loop for rading lines of source code into input buffer
while(gets(input))
{
lexemeBegin = 0;
while(input[lexemeBegin]!='\0'&&input[lexemeBegin]!='\n' &&input[lexemeBegin]!='\r') //while end of line is not found
{
while(input[lexemeBegin]==' ' || input[lexemeBegin] == '\t')
lexemeBegin++;
//checking for keywords and identifiers
t = identifier_keyword(input);
if(t.tokenID!=NOTOK)
{
write_token(t);
continue;
}
//checking for integer constants
t = integer_constant(input);
if(t.tokenID!=NOTOK)
{
write_token(t);
continue;
}
//checking for floating point number constants
t = float_constant(input);
if(t.tokenID!=NOTOK)
{
write_token(t);
continue;
}
//checking for arithmetic operators
t = arithmetic_operator(input);
if(t.tokenID!=NOTOK)
{
write_token(t);
continue;
}
//checking for assignment operators
t = assignment_operator(input);
if(t.tokenID!=NOTOK)
{
write_token(t);
continue;
}
//checking for relational operators
t = relational_operator(input);
if(t.tokenID!=NOTOK)
{
write_token(t);
continue;
}
//checking for special symbols
t = special_symbol(input);
if(t.tokenID!=NOTOK)
{
write_token(t);
continue;
}
//checking for comments
comment(input);
//checking erroneous lexeme
error_condition(input);
}
}
}
