我的输出显示一些奇怪的符号
我必须为班级编码.编码是关于要求用户键入其姓名,年龄和ID.然后,程序应根据其姓名中的前6个字母,年龄和学生ID中的前两个字母来获取密码.问题是输出中的符号(╠╠╠╠╠╠╠╠╠╠╠╠╠╠)不确定.谁能告诉我为什么它在那里?然后,它应该计算并显示密码的长度.这是代码:
I had to a coding for my class. The coding is about asking the user to type their Name, age and id. An then the program should for a passcode based on the first 6 letter in their name, their age and the first two letter in their student id. The problem is the a unidentified symbol (╠╠╠╠╠╠╠╠╠╠╠╠╠╠ )in the output. Can anyone tell me why it is there>? Then it should calculate and display the lenght of the passcode. Here is the code:
#include <stdio.h>
#include <string.h>
void main(void)
{
char name[20], id[9], age[3], passcode[10];
int x;
puts("Enter your name:\n");
gets(name);
puts("\nEnter your student id:\n");
gets(id);
puts("\nEnter your age:\n");
gets(age);
x = strlen(passcode);
strncpy(passcode, name, 6);
strncat(passcode, id, 2);
printf("The passcode is:%s \n",passcode);
printf("The passcode has %d characters..\n",x);
}
它看起来像:
Enter your name:
johnny
Enter your student id:
dc87671
Enter your age:
20
The passcode is:johnny╠╠╠╠╠╠╠╠╠╠╠╠╠╠20dc
The passcode has 22 characters..
Press any key to continue . . .
密码有22个字符
The passcode has 22 characters
但是您为密码分配了10个字符的缓冲区
And yet you allocated a buffer of 10 characters for passcode
passcode[10]
您不是空终止密码.来自 strncpy
You are not null terminating passcode. Note from strncpy
如果source大于num,则不会在目标末尾隐式附加空字符.因此,在这种情况下,目的地不应被视为以null终止的C字符串(这样读取它会溢出).
No null-character is implicitly appended at the end of destination if source is longer than num. Thus, in this case, destination shall not be considered a null terminated C string (reading it as such would overflow).
另请注意,该行
x = strlen(passcode);
在初始化之前对密码起作用.这样,它将包含随机位,从而导致x的值定义不明确.您目前不使用x,因此它不会直接影响当前的问题.
is acting on passcode before it is initialized. As such, it will contain random bits, rendering the value of x not well defined. You do not use x currently, so it is not directly affecting the issue at hand.