scanf(..);輸入字元按下回車鍵後，gets()函式會把回車鍵當做輸入的字元。所以在執行gets()前要把回車過濾掉！！

改正後程式碼：

#include

main()

{

char a1[5] = "",a2[5] = "",a3[5] = "",a4[5] = "";

scanf("%s%s",a1,a2);

printf("a1=%s\n",a1);

printf("a2=%s\n",a2);

printf("a3=%s\n",a3);

printf("a4=%s\n",a4);

printf("請輸入a3:");

getchar(); //過濾回車

gets(a3);printf("a1=%s\n",a1);

printf("a2=%s\n",a2);

printf("a3=%s\n",a3);

printf("a4=%s\n",a4);

printf("請輸入a4:");

gets(a4);

/*puts(a1);

puts(a2);

puts(a3);

puts(a4);*/

printf("a1=%s\n",a1);

printf("a2=%s\n",a2);

printf("a3=%s\n",a3);

printf("a4=%s\n",a4);

}