The regular solution (Marius Gavrilescu)

Since format specifiers are whole words, we can iterate through the words of the format string, passing each of them to printf (with an argument if needed). We will use a std::map to map variable names to values.

    1 #include<cstdio>
    2 #include<cstdlib>
    3 #include<cstring>
    4 #include<map>
    5 
    6 std::map<char, char*> vars; // Map from variable names to values
    7 char c, s[105], *vs;        // vs points to the name of the previous variable
    8 
    9 char* next() {              // This function returns the name of the next variable
   10     vs+=2;                  // Advance to the next variable name
   11     return vars[*vs];       // Return the value of the variable
   12 }
   13 
   14 int main(){
   15     int n;
   16     scanf("%d ", &n);           // Read the number of variables
   17     while(n--){
   18         scanf("%c=%s ", &c, s); // Read the variable name and value
   19         vars[c] = strdup(s);    // Store the variable in the map
   20     }
   21     fgets(s, 105, stdin);       // Read the last line
   22 
   23     vs = strchr(s, ',') - 1;    // Two characters before the first variable name
   24     vs[1] = 0;                  // Remove the comma to terminate the format string here
   25 
   26     for(char *w = strtok(s, " "); w != NULL; w = strtok(NULL, " ")){
   27         char type = w[strlen(w) - 1]; // The last character of this word, e.g. d for %5d
   28         if(w[0] != '%')               // If the word is not a format specifier...
   29             printf(w);                // ...print it directly
   30         else if(type == 's')          // If the format specifier ends with a s...
   31             printf(w, next());        // ...pass it to printf as-is (= as a string)
   32         else if(type == 'd')          // If the format specifier ends with a d...
   33             printf(w, atoi(next()));  // ...pass it to printf as an int
   34         else                          // Otherwise (if it ends with a f)...
   35             printf(w, atof(next()));  // ...pass it to printf as a float
   36         putchar(' ');                 // Put a space after this word
   37     }
   38 
   39     return 0;
   40 }

The easy solution (Marius Gavrilescu)

An easier way to solve this problem is to directly call printf with the given format string and arguments. This can't be done portably in C. Fortunately, some other languages do not have this restriction.

    1 #!/usr/bin/perl
    2 use v5.14;
    3 use warnings;
    4 
    5 my @args = <>;                              # Read all lines
    6 chomp @args;                                # Remove the final newline from all lines
    7 shift @args;                                # Get rid of the first line
    8 my ($format, @vars) = split ',', pop @args; # Split the last line into a format string and variables
    9 my %args = map { split '=' } @args;         # Create a hash from variable names to values
   10 
   11 printf $format, map { $args{$_} } @vars;    # Pass the format string and variable values to printf