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Unsigned char looping

What is an elegant way to do something like this without going into an infinite loop if i should be an unsigned char ?

 for (unsigned char i = 0; i < 256; ++i) { printf("%d\n", i); }
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3 answers
 unsigned char i = 0; do { printf("%u\n",i); }while(++i != 0);

Increment the loop test and test it with the wrapped value.

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As a general rule: if your iterator variable must contain all values ​​between 0 and "Uxxx_MAX", you have chosen a too narrow type for the algorithm.

Instead, you should have used uint16_t .

There are so many cases where you cannot use a large int type instead of your unsigned char. So let me ask you, your application is an embedded real-time system written for an 8-bit MCU, where did you find that this very loop is a performance bottleneck?

  • If so, write an obscure loop with uint8_t as an iterator type and comment on why you did it.
  • If not, use uint16_t or a larger integer type.
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Place check after body and before increment

 for (unsigned char i = 0; ; ++i) { printf("%d\n", i); if(i==255) break; }

But then you can also do the following:

 unsigned char i = 0; while( ) { printf("%d\n", i); if(i==255) break; ++i; }

Or even hit check:

 for (unsigned char i = 0; i++ < 255; ) { printf("%d\n", i); }

They all check the value 255 before incrementing, instead of checking for zero after that, so if the variable was a CHAR or some macro that is currently limited to 256 but can be changed, they will still work, since they don’t rely on overflow. Replace int there, and it still works.

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