Print minimum number of digits

Using Arduino Programming Questions
#1

What is the best way to "print" (Serial.print) an integer with a specified minimum number of digits (ex. printf("%03d", 1) -> 001)?

#2

What is the best way to "print" (Serial.print) an integer with a specified minimum number of digits (ex. printf("%03d", 1) -> 001)?

Use sprintf() to print to a buffer, then Serial.print() the buffer. It's really the only way. That makes it the best way automatically.

#3

if it's less than 1000, print a zero if it's less than 100, print a zero if it's less than 10, print a zero print the number

but that's better done in a loop that starts with 1000 and divides by 10 until less than 10.

I've worked it to make fixed-point integers print fast.

#4

PaulS: Use sprintf() to print to a buffer, then Serial.print() the buffer. It's really the only way. That makes it the best way automatically.

I thought about that but I didn't thing that would be the preferred way because printf and friends (sprintf, fprintf, vsprintf, etc...) tend to use a lot of program (FLASH) space.

#5

but that’s better done in a loop that starts with 1000 and divides by 10 until less than 10.

I would disagree here. The loop approach is harder to implement and will consume a lot more memory because the Arduino lacks hardware division. The approach with the if statements is much simpler and compiles to less instructions.

Even in case of variable digits I would stick with the if statements like so:

switch (digits) {
    case 5: { if (n<10000) { print('0'); }}
    case 4: { if (n<1000)  { print('0'); }}
    case 3: { if (n<100)   { print('0'); }}
    case 2: { if (n<10)    { print('0'); }}
}
print(n);
#6