C Interview Questions Part 1

Q: In printf() Function- What is the difference between "printf(...)" and "sprintf(...)"?
A: sprintf(...) writes data to the character array whereas printf(...) writes data to the standard output device.

Q:Compilation How to reduce a final size of executable?

A:Size of the final executable can be reduced using dynamic linking for libraries.

Q:Linked Lists -- Can you tell me how to check whether a linked list is circular?
A:Create two pointers, and set both to the start of the list. Update each as follows:
while (pointer1) {
pointer1 = pointer1->next;
pointer2 = pointer2->next;
if (pointer2) pointer2=pointer2->next;
if (pointer1 == pointer2) {
print ("circular");
If a list is circular, at some point pointer2 will wrap around and be either at the item just before pointer1, or the item before that. Either way, its either 1 or 2 jumps until they meet.

Q:string Processing --- Write out a function that prints out all the permutations of a string. For example, abc would give you abc, acb, bac, bca, cab, cba.
A:void PrintPermu (char *sBegin, char* sRest) {
int iLoop;
char cTmp;
char cFLetter[1];
char *sNewBegin;
char *sCur;
int iLen;
static int iCount;
iLen = strlen(sRest);
if (iLen == 2) {
printf("%d: %s%s\n",iCount,sBegin,sRest);
printf("%d: %s%c%c\n",iCount,sBegin,sRest[1],sRest[0]);
} else if (iLen == 1) {
printf("%d: %s%s\n", iCount, sBegin, sRest);
} else {
// swap the first character of sRest with each of
// the remaining chars recursively call debug print
sCur = (char*)malloc(iLen);
sNewBegin = (char*)malloc(iLen);
for (iLoop = 0; iLoop <>
strcpy(sCur, sRest);
strcpy(sNewBegin, sBegin);
cTmp = sCur[iLoop];
sCur[iLoop] = sCur[0];
sCur[0] = cTmp;
sprintf(cFLetter, "%c", sCur[0]);
strcat(sNewBegin, cFLetter);
debugprint(sNewBegin, sCur+1);
void main() {
char s[255];
char sIn[255];
printf("\nEnter a string:");
PrintPermu(s, sIn);