What is the difference between 'a' and "a"?
Does the following code terminate? And if so, under which conditions?
char i, j;
for (i = 0; i < 10, j < 5; i++, j++);
Write an implementation of bubble sort for a fixed array of integers.
An array of integers can be defined as int i[] = {1, 2, 3, 4};
Modify youur answer to sort characters into lexicographical order.
Use function recursion to write an implementation of merge sort for a fixed array of integers; how much memory does your program use for a list of length n?
Implement a function int cntlower(char str[]) that, given a string, returns the number of lower-case letters it contains.
Define a macro SWAP(t, x, y) that swaps two arguments x and y of type t. Does your macro work as expected for
SWAP(int, v[i++], w[f(x)])
What other invocations could cause a simple implementation to fail and how can we mitigate them?
Define a macro SWAP(x, y) that swaps x and y of the same type without using any extra memory.
Given a pointer p, what does the expression p[-2] mean, and when is it legal?
If p is a pointer to a structure, write some C code which uses all the following indirections:
++p->i
p++->i
*p->i
*p->i++
(*p->i)++
*p++->i
and describe the action of each code line.
Write a string search function with a declaration of
char *strfind(const char *s, const char *f);
which returns a pointer to the first occurrence of s in f (and NULL otherwise)
Write a program calc which evaluates an expression in Reverse Polish Notation given on the command line; for example
$ calc 2 3 4 + \*
should print 14. The character * needs to be escaped with a backslash in some shells or otherwise it gets expanded to all the files in your current directory.
What is the value of i after executing each of the following:
i = sizeof(char);i = sizeof(int);int a; i = sizeof a;char b[5]; i = sizeof(b);char *c=b; i = sizeof(c);struct { int d; char e;} s; i = sizeof s;void f(int j[5]) { i = sizeof j;}void f(int j[][10]) { i = sizeof j; }According to the rules of pre and post increment what would you expect these expressions to do:
i++ + ++i
++i + ++i
What actually happens if you try it?
A spacecraft arrives on Mars, but its memory has been corrupted by radiation en
route. Luckily, it can receive updates one bit at a time using a predefined C
function short receive_bit(void), that when called will return either 1 or 0.
The stream of bits for a value is transmitted in unsigned big-endian byte order:
for example, a 16-bit value of 125 would be 0000000001111101. Assume the int
type is 32 bits.
Explain the meaning of the inline keyword on C function declarations, and a
potential drawback of using it.
Using receive_bit(), define a function receive_int() that decodes and
returns a 32-bit value from the sequence of received bits.
(optional) Build a more general decoding function receive using a C++ template with two parameters that specify the number of bits to decode and a datatype for the decoded value. Use this to write two template instantiations that decode an 8-bit value into a short and a 32-bit value into an unsigned long.
Find and explain four instances of undefined behaviour that could result
from compiling and running the C code below with different command-line
arguments.
The strcpy(dst,src) function copies a zero-terminated C string from the
src buffer to the dst buffer. The putchar(c) function outputs a
character c to the console. You can assume that the standard C header
prototypes have been included for <stdio.h>, <stdlib.h> and <string.h>.
char *show_instruction(int msg) {
char buf[6];
int fuel;
if (msg == 1 && fuel--) {
strcpy(buf, "THRUST");
return buf;
} else if (msg == 2) {
char *msg = (char *)malloc(100);
strcpy(msg, "DEPLOY_PARACHUTE");
return msg;
}
}
int main(int argc, char **argv) {
char *msg;
msg = show_instruction(argc);
putchar(msg[0]);
return 0;
}