interpolating a value into a formatting string

[bitwise]

I'm trying to generate some dynamic string padding so things line up correctly, well my question is, how can I get a variable value into a printf string statement so that it is not hardcoded in. For example,

int val=10;
printf("%-5s:%s", str1, str2);

That would right-align things padding the strings by 5 via the difference from the length of str1 and 5.

he :str2
hello:str2
see :str2

Well, what if I wanted to use 'val' instead of 5. How can I have printf use the value of 'val' instead? Is this possible?

Thanks,
-bitwise

 

[hnd]

Use sprintf instead of printf

for Example:

char formatstr[nn];

sprintf(formatstr,"format",arguments);
printf(formatstr, parm1,parm2.....);

hnd
hasso55@yahoo.com

 

[bitwise]

That is not going to work. I still run into the same problem, namely not being able to put the value of 'val' into the string correctly. For example,

char formatstr[nn];

sprintf(formatstr, "%-%ds:%s\n", val, str1, str2);
printf(formatstr);

That does not work. val does not get placed into the formatting string, it gets confused. This works:

sprintf(formatstr, "%-5s:%s\n", str1, str2);
printf(formatstr);

But that is not what I want. I want to change the value of 5 to something I compute at runtime to achieve dynamic padding. I just want to replace 5 with a variable name, but I can't seem to find a way to do it.

Thanks,
bitwise

 

[rbobbitt]

You have to precede % characters with another '%' to unconfuse sprintf(). Try something like this:

char formatstr[N];
char str1[]="foo";
char str2[]="bar";
int val=10;

sprintf(formatstr,"%%-%dd%s:%s\n",val,str1,str2);
printf(formatstr,40);

Russ
bobbitts@hotmail.com

http://home.earthlink.net/~bobbitts

 

[bitwise]

Thanks, guys! I've got it working now, and have learned yet another trick thanks to the programming talents on this forum - man I'm glad I found this place.

Thanks,
-bitwise