This warning is gcc’s way of telling you that it cannot verify the format string argument to the printf style function (printf, fprintf… etc). This warning is generated when the compiler can’t manually peek into the string and ensure that everything will go as you intend during runtime. Lets look at a couple of examples. … Read more
You can use the %g format specifier: #include <stdio.h> int main() { float f1 = 12; float f2 = 12.1; float f3 = 12.12; float f4 = 12.1234; printf(“%g\n”, f1); printf(“%g\n”, f2); printf(“%g\n”, f3); printf(“%g\n”, f4); return 0; } Result: 12 12.1 12.12 12.1234 Note that, unlike the f format specifier, if you specify a … Read more
%02x means print at least 2 digits, prepend it with 0‘s if there’s less. In your case it’s 7 digits, so you get no extra 0 in front. Also, %x is for int, but you have a long. Try %08lx instead.
In Bash: var=$(printf ‘FILE=_%s_%s.dat’ “$val1” “$val2”) or, the equivalent, and closer to sprintf: printf -v var ‘FILE=_%s_%s.dat’ “$val1” “$val2” If your variables contain decimal values with leading zeros, you can remove the leading zeros: val1=008; val2=02 var=$(printf ‘FILE=_%d_%d.dat’ $((10#$val1)) $((10#$val2))) or printf -v var ‘FILE=_%d_%d.dat’ $((10#$val1)) $((10#$val2)) The $((10#$val1)) coerces the value into base 10 … Read more
printf() doesn’t directly support that. Instead you have to make your own function. Something like: while (n) { if (n & 1) printf(“1”); else printf(“0”); n >>= 1; } printf(“\n”);
For variable argument functions like printf and scanf, the arguments are promoted, for example, any smaller integer types are promoted to int, float is promoted to double. scanf takes parameters of pointers, so the promotion rule takes no effect. It must use %f for float* and %lf for double*. printf will never see a float … Read more
There is no way to tell sprintf() not to write a trailing null. What you can do is use sprintf() to write to a temporary string, and then something like strncpy() to copy only the bytes that you want.
%d represents an integer; you want to use %f for a double. See the formatting string syntax in the Javadoc
It doesn’t differentiate. It’s not possible to receive a float as a vararg: any float argument that you provide is first promoted to double. 6.5.2.2/6 defines “default argument promotions”, and /7 states that default argument promotions are applied to “trailing arguments”, that is varargs denoted by …. how does it work for scanfs/sscanf? The %f … Read more
That’s because the format parameter is not actually a string. It’s TextWriterFormat<‘T> and the F# compiler converts the string format into that type. But it doesn’t work on string variables, because the compiler can’t convert the string to TextWriterFormat<‘T> at runtime. If you want to print the content of the variable, you shouldn’t even try … Read more