你能解释一下这个C程序的输出吗？

#include <stdio.h>
#include <string.h>

main() {
    int i = 0, j = 0;
    char ch[] = { "chicken is good" };
    char str[100];
    while ((str[i++] = ch[j++]) != '
 
 
#include <stdio.h>
#include <string.h>

main() {
    int i = 0, j = 0;
    char ch[] = { "chicken is good" };
    char str[100];
    while ((str[i++] = ch[j++]) != '\0') {
        if (i == strlen(str))
            break;
    }
    printf("%s", str);
}
 
 
I want to copy the string "chicken is good" from ch to str using a while loop. But when I print str the output shows "chi". It only prints part of the string. Is my condition wrong?
 
 
我想使用while循环将字符串“chicken is good”从ch复制到str。但是当我打印str时,输出显示“chi”。它只打印部分字符串。我的病情错了吗?
 
 
I am using Dev c++ as my IDE and the version of my compiler is gcc 4.9.2. And also I am new to programming.
 
 
我使用Dev c ++作为我的IDE,我的编译器版本是gcc 4.9.2。而且我也是编程新手。
 
  
  
 
2 个解决方案
 
 
 
  
#1
 
  
 
  
 
   
2  
 
   
strlen(str) has undefined behaviour, because it is reading uninitialized values.
 
   
strlen(str)具有未定义的行为,因为它正在读取未初始化的值。
 
  
 
 
 
 
 
  
#2
 
  
 
  
 
   
3  
 
   
The statement if (i == strlen(str)) break; is useless and has undefined behavior since str is not yet null terminated.
 
   
语句if(i == strlen(str))中断;由于str尚未终止,因此无用且具有未定义的行为。
 
   
Note that your program has other problems:
 
   
请注意,您的程序还有其他问题:
 
   
 
    
you must specify the return value of the main function as int. You are using an obsolete syntax.
 
    
必须将main函数的返回值指定为int。您使用的是过时的语法。
 
    
you do not need separate index variables i and j for the source and destination arrays. They always have the same value.
 
    
对于源和目标数组,您不需要单独的索引变量i和j。它们总是具有相同的价值。
 
    
you should print a newline at the end of your message.
 
    
您应该在邮件末尾打印换行符。
 
    
for good style, you should return 0 at the end of main().
 
    
为了好的风格,你应该在main()的末尾返回0。
 
   
 
   
Here is a simpler version:
 
   
这是一个更简单的版本:
 
   
#include <stdio.h>

int main(void) {
    int i;
    char ch[] = "chicken is good";
    char str[100];

    for (i = 0; (str[i] = ch[i]) != '\0'; i++) {
        continue;
    }
    printf("%s\n", str);
    return 0;
}
 
  
 
 
 

') {
        if (i == strlen(str))
            break;
    }
    printf("%s", str);
}
#include <stdio.h>
#include <string.h>

main()