c - 如何在不使用strcmp的情况下比较两个二维字符串

Question

我有数据文件，其中保存了一些数据。示例:欢迎用户 HII if while
我制作了二维字符数组来存储c中的所有关键字。现在我想知道数据文件是否包含关键字。

enter code here
  for(i=0;i<32;i++)
  for(j=0;j<no_of_words_in_file;j++)
      if(k[i]==t[j])
         printf("%s is keyword",t[j]);

这里的k[i]表示存放c中所有关键字的二维字符数组，t[i]表示存放file中所有单词的二维字符数组。我想在不使用 strcmp 的情况下比较这些二维数组。

Answer 1

要比较两个字符串而不使用标准 C 函数，您可以使用这样的循环

#include <stdio.h>

int main(void) 
{
    char key[]   = "while";
    char word1[] = "while";
    char word2[] = "when";

    size_t i = 0;

    while ( key[i] != '\0' && key[i] == word1[i] ) ++i;

    int equal = key[i] == word1[i];

    printf( "key == word1: = %d\n", equal );

    i = 0;

    while ( key[i] != '\0' && key[i] == word2[i] ) ++i;

    equal = key[i] == word2[i];

    printf( "key == word2: = %d\n", equal );

    return 0;
}

程序输出为

key == word1: = 1
key == word2: = 0

或者你可以编写一个单独的函数。例如

#include <stdio.h>

int equal( const char *s1, const char *s2 )
{
    while ( *s1 != '\0' && *s1 == *s2 ) 
    {
        ++s1; ++s2;
    }

    return *s1 == *s2;
}

int main(void) 
{
    enum { N = 10 };
    char key[][N] ={ "if",  "while" };
    const size_t N1 = sizeof( key ) / sizeof( *key );
    char words[][N] = { "welcome", "user", "HII", "if",  "while" };
    const size_t N2 = sizeof( words ) / sizeof( *words );

    for ( size_t i = 0; i < N2; i++ )
    {
        for ( size_t j = 0; j < N1; j++ )
        {
            if ( equal( key[j], words[i] ) )
            {
                printf( "\"%s\" == \"%s\"[%zu]\n", key[j], words[i], i );
            }               
        }
    }

    return 0;
}

程序输出为

"if" == "if"[3]
"while" == "while"[4]