how to do "" in printf c++ code example

Example: printf in c++

#include <cstdio>

int main()
{
    char ch = 'a';
    float a = 5.0, b = 3.0;
    int x = 10;

    printf("%.3f / %.3f = %.3f \n", a,b,a/b);
    printf("Setting width %*c \n",5,ch);
    printf("Octal equivalent of %d is %o \n",x,x);

    return 0;
}