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C Programming, Review Questions
None edited this page Jan 14, 2020
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- 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
sizeofreturn for one of them?
char str1[] = "another";
char *str2 = "another one";- What is a string in c?
- Code up a simple
my_strcmp. How aboutmy_strcat,my_strcpy, ormy_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 thancalloc. Once memory ismalloced how can I userealloc? - 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, orchar? - Is the following code valid? If so, why? Where is
outputlocated?
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'sFILE*internally or vice versa?
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