关于#C语言#字符串函数的问题，如何解决？

Question

这里为什么会多个引号呢？ 明明两次都是拼接的"非"

源码：

#include <stdio.h>
#include <string.h>
#define SENT_LEN 5
#define WORDS_NUM 2
#define STR_LEN 101

int main(int argc, char** argv)
{
    int i, j;
    char words[SENT_LEN][STR_LEN] = {"非","淡泊","无以","明志","!"};
    char source[WORDS_NUM][STR_LEN] = {"淡泊","明志"};
    char target[WORDS_NUM][STR_LEN] = {"宁静","致远"};
    char sentence_before[STR_LEN];
    char sentence_after[STR_LEN];
    
    for (i = 0; i < SENT_LEN; ++i)
    {
        strcat(sentence_before, words[i]);
        for (j = 0; j < WORDS_NUM; ++j)
            if (strcmp(words[i], source[j]) == 0)
                strcpy(words[i], target[j]);
        strcat(sentence_after, words[i]);
    }
    
    puts("替换前：");
    puts(sentence_before);
    puts("替换后：");
    puts(sentence_after);

    return 0;
}

Answer 1

 char sentence_before[STR_LEN] = {0};
    char sentence_after[STR_LEN] = {0};

数组要初始化为0，否则没有字符串结束符