宏參數與字串

#include <stdio.h>//鄰近字串會自動連接,"A""B" 相當於"AB"#define PRINT(FORMAT, VALUE)        \    printf("The value of "   #VALUE   " is "\            FORMAT "\n", VALUE)#define PRINT_USE_NUMBER_SIGN(FORMAT, VALUE)        \    printf("The value of "   #VALUE   " is "\    #FORMAT "\n", VALUE)//## 預先處理時，將位於兩邊的符號串連成一個符號#define ADD_TO_SUM(sum_number, value) \    sum ## sum_number += valueint main (){    int sum5 = 1;    PRINT("%d", 3 + 1);    PRINT_USE_NUMBER_SIGN(%d, 3 + 1);    //宏參數前面加個Number Sign (#),預先處理會將該宏參數轉換為字串    //故PRINT_USE_NUMBER_SIGN中的%d不用加雙引號    ADD_TO_SUM(5, 10);    printf("%d\n", sum5);    return 0;}$ gcc -E 1.c    printf("The value of " "3 + 1" " is " "%d" "\n", 3 + 1);    printf("The value of " "3 + 1" " is " "%d" "\n", 3 + 1);    sum5 += 10;$ ./1The value of 3 + 1 is 4The value of 3 + 1 is 411