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I'm trying to output some numbers in a log file and I want to pad a load of floats via the printf function to produce:
058.0 020.0 038.0 -050.0 800.0 150.0 100.0 Currently I'm doing this:
printf("% 03.1f\n", myVar); ...where myVar is a float. The output from that statement looks like this:
58.0 20.0 38.0 -50.0 800.0 150.0 100.0 From what I've read I would expect my code to produce the output I mentioned at the top of this post, but clearly something is wrong. Can you only use one flag at a time? ..or is there something else going on here?
379
The # is a flag that modifies the output of the format specifier (which you don't provide in your string).
The %a formatting specifier is new in C99. It prints the floating-point number in hexadecimal form. This is not something you would use to present numbers to users, but it's very handy for under-the-hood/technical use cases. As an example, this code: printf("pi=%a\n", 3.14); prints: pi=0x1.91eb86p+1.
printf allows formatting with width specifiers. For example, printf( "%-30s %s\n", "Starting initialization...", "Ok." ); You would use a negative width specifier to indicate left-justification because the default is to use right-justification.
The printf function of C can do a lot more than just printing the values of variables. We can also format our printing with the printf function. We will first see some of the format specifiers and special characters and then start the examples of formatted printing.
The width specifier is the complete width:
printf("%05.1f\n", myVar); // Total width 5, pad with 0, one digit after . To get your expected format:
printf("% 06.1f\n", myVar); If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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