CODEWITHSUNDEEP
cprintfformat-string
Marjan
Marjan

Reputation: 149

printf() precision

char buf[10];
int counter, x = 0;
snprintf (buf, sizeof buf , "%.100d%n", x, &counter); 
printf("Counter: %d\n", counter)

I am learning about precision with printf. With %.100d%n, the precision here gives 100 digits for rendering x.

What I don't understand is why would the counter be incremented to 100, although only 10 characters are actually written to the buffer?

Upvotes: 1

Views: 230

Answers (1)

pmg
pmg

Reputation: 108938

The ten bytes written to buf are 9 spaces and 1 '\0' (zero terminator), counter is assigned the value 100 for 99 spaces and 1 '0' (digit zero).

   buf <== "         "
%.100d <== "          .....   0"

Note that buf is incomplete: it does not have a '0'.

Upvotes: 1

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