有没有办法在C中传递这样的字符串？

Question

I have a function which accepts a character array (ie, string) as argument.

But an integer variable's value should also be printed as part of string.

For example, If I have a function like this:

int var=10;
void printStr(char str[])
{
   printf("%s", str);
}

and I need to print the value of integer variable 'var' with a message

"The value of var is %d", var

I tried this

printStr( ("The value of var is %d", var) );

but it didn't work.

Is there a way to accomplish this without passing the variable as argument to printStr() ?

The output in this case should be

The value of var is 10

Answer 1

It seems that you need the function sprintf / snprintf for generation of the string.

Try something like this:

char tempStr[30];
snprintf(tempStr, sizeof(tempStr), "The value of var is %d", var);
printStr(tempStr);

Is it what you need?

Answer 2

Perhaps you might find variable number of arguments to functions and the GCC format attributes useful to building your thing. You'll need to be using GCC for the attributes however, and not have any plans of being portable to other compilers.

I would not mess with these things however, and figure out a way to do things without this.