how to fix this unexpected output? - c

Question

I have been doing on decomposing Integers to prime numbers, but i got stucked , it s working for one prime number, but when the iteration continues then it s not working properly and I can t come up with any solution.
For example for number 12 i expect output 2^2 x 3
but instead program stops at 2^2 x and new input is expected.
int main(int argc, char *argv[])
{
int number;
int stop = 1;
int prime = 0;
int sqr = 0;
while (stop == 1) {
/**------ERROR------ **/
if(scanf("%d",&number) != 1 || number < 0 ){
fprintf(stderr,"%s","Error: Chybny vstup!\n");
return 100;}
if(number == 0){
stop = 0;
break;}
/**------DECOMPOSITION------ **/
for (int index = 1;index <=number;){
if(number == 1){
//Ak sa input cislo rovna 1 tak vypise nasledovne riadky
printf("Prvociselny rozklad cisla 1 je:\n");
printf("1\n");
break;}
if(number % (index + 1) == 0){
// ak je cislo % index +1 (pociatocna hodnota je 2) tak sa vydeli cislom index + 1
// do prime sa ulozi dane prvocislo
// ak je delitelne prvocislom pripocitame sqr +1
// cyklus pokracuje s rovnakym indexom
number = number / (index + 1);
prime = index + 1;
sqr = sqr + 1;
continue;}
else{
if(sqr == 1){
// vypise len prvocislo
printf("%d",prime);}
if(sqr != 1){
//vypise prvocislo aj mocninu
printf("%d^%d", prime,sqr);}
if(number != 1){
printf(" x ");}
else{
printf("\n");
break;}
}
index = index + 1;
sqr = 0;
}
}
return 0;
}

Answer 1

I see two problems in the code:
The special case for number == 1 is being handled inside the loop. That special case is much easier to handle before the loop.
Counting the exponent is mixed into the loop that updates the factor. It's much easier to use a second loop to count the exponent.
#include <stdio.h>
int main(void)
{
while (1){
/**------GET USER INPUT------ **/
int number;
if(scanf("%d",&number) != 1 || number < 0 ){
fprintf(stderr,"%s","Error: Chybny vstup!\n");
return 100;
}
/**------HANDLE SPECIAL CASES------ **/
if(number == 0){
break;
}
if(number == 1){
printf("Prvociselny rozklad cisla 1 je:1\n");
continue;
}
/**------DECOMPOSITION------ **/
for (int factor = 2; factor <= number; factor++){
int exponent = 0;
while(number % factor == 0){
number /= factor;
exponent++;
}
if (exponent == 1){
printf("%d", factor);}
else if (exponent > 1){
printf("%d^%d", factor, exponent);}
if(exponent != 0 && number != 1){
printf(" x ");}
}
printf("\n");
}
}