- C Strings representation
- C Strings as pointers
- char p[]vs char* p
- Simple C string functions (strcmp, strcat, strcpy)
- sizeof char
- sizeof x vs x*
- Heap memory lifetime
- Calls to heap allocation
- Deferencing pointers
- Address-of operator
- Pointer arithmetic
- String duplication
- String truncation
- double-free error
- String literals
- Print formatting.
- memory out of bounds errors
- static memory
- fileio POSIX vs. C library
- C io fprintf and printf
- POSIX file IO (read, write, open)
- Buffering of stdout
- What does the following print out
int main(){
fprintf(stderr, "Hello ");
fprintf(stdout, "It's a small ");
fprintf(stderr, "World\n");
fprintf(stdout, "place\n");
return 0;
}
- What are the differences between the following two declarations? What does
sizeof return for one of them?
char str1[] = "another";
char *str2 = "another one";
- What is a string in c?
- Code up a simple
my_strcmp. How about my_strcat, my_strcpy, or my_strdup? Bonus: Code the functions while only going through the strings once.
- What should the following usually return?
int *ptr;
sizeof(ptr);
sizeof(*ptr);
- What is
malloc? How is it different than calloc. Once memory is malloced how can I use realloc?
- What is the
& operator? How about *?
- Pointer Arithmetic. Assume the following addresses. What are the following shifts?
char** ptr = malloc(10); //0x100
ptr[0] = malloc(20); //0x200
ptr[1] = malloc(20); //0x300
* `ptr + 2`
* `ptr + 4`
* `ptr[0] + 4`
* `ptr[1] + 2000`
* `*((int)(ptr + 1)) + 3`
- How do we prevent double free errors?
- What is the printf specifier to print a string,
int, or char?
- Is the following code valid? If so, why? Where is
output located?
char *foo(int var){
static char output[20];
snprintf(output, 20, "%d", var);
return output;
}
- Write a function that accepts a string and opens that file prints out the file 40 bytes at a time but every other print reverses the string (try using POSIX API for this).
- What are some differences between the POSIX filedescriptor model and C's
FILE* (ie what function calls are used and which is buffered)? Does POSIX use C's FILE* internally or vice versa?