请教程序中的双引号什么意思
#include <stdio.h>int main( void )
{
int lower, upper, index;
int square, cube;
printf("Enter starting integer: ");
scanf("%d", &lower);
printf("Enter ending integer: ");
scanf("%d", &upper);
printf("%5s %10s %15s\n", "num", "square", "cube");
for (index = lower; index <= upper; index++)
{
square = index * index;
cube = index * square;
printf("%5d %10d %15d\n", index, square, cube);
}
return 0;
}请问红色那句程序是什么意思呢，为什么要加双引号呢？
