display palindrome from 1 to n

Question

plz use loops only

Answer 1

Here is my shot at it:

http://www.sololearn.com/app/cplusplus/playground/cTwgvFvpR1nu/

void printPalindromes(unsigned int n) {
unsigned int i, num, pal;
bool numDigitsEven;
pal = 1;
numDigitsEven = false;
for (num = 1; pal < n; num++) {
pal = num;
if (numDigitsEven) {
i = num;
} else {
i = num/10;
}
for (; i > 0; i = i/10) {
pal = pal*10 + i%10;
}
cout << pal << endl;
for (i = num; i%10==9; i=i/10) {}
if (i == 0) {
if (!numDigitsEven) {
num = num/10;
numDigitsEven = true;
} else {
numDigitsEven = false;
}
}
}
}

An alternative version, which is probably the standard way to do it (but is slower):

void printPalindromes2(unsigned int n) {
unsigned int i, rev, i2;
for (i = 1; i <= n; i++) {
i2 = i;
rev = 0;
while (i2 > 0) {
rev = rev*10 + i2%10;
i2 = i2/10;
}
if (rev == i) {
cout << i << endl;
}
}
}