printf的格式说明符
%c 打印单个ASCII 字符 printf("The character is %c\n",x) 输出: The character is A %d 打印一个十进制数 printf("The boy is %d years old\n",y) 输出:The boy is 15 years old %e 打印数字的e 记数法形式 printf("z is %e\n",z) 打印: z is 2.3e+0 1 %f 打印一个浮点数 printf("z is %f\n", 2.3 * 2) 输出: z is 4.600000 %o 打印数字的八进制 printf("y is %o\n",y) 输出:z is 17 %s 打印一个字符串 print("The name of the culprit is %s\n",$1) 输出:The name of the culprit is Bob Smith %x 打印数字的十六进制值 printf("y is %x\n",y) 输出:x is f