📜  编写自己的忽略大小写的strcmp

📅  最后修改于: 2021-05-25 07:11:50             🧑  作者: Mango

编写一个修改后的strcmp函数,该函数将忽略大小写,如果s1

资料来源:Microsoft Interview Set 5

以下解决方案假设字符使用ASCII表示,即表示为’A’, ‘B’, ‘C’的代码,… ‘Z’是97,98,99,…分别122。 “ A”,“ B”,“ C”,……“ Z”的代码分别为65、66,……95。

以下是详细步骤。
1)遍历两个字符串的每个字符,并对每个字符进行跟随。
a)如果str1 [i]与str2 [i]相同,则继续。
b)如果将str1 [i]的第六个最低有效位取反,使其与str2 [i]相同,则继续。例如,如果str1 [i]为65,则将第6位取反将使其变为97。如果str1 [i]为97,则将第6位取反将使其变为65。
c)如果以上两个条件中的任何一个都不成立,则中断。
2)比较最后一个(或第一个不匹配的字符)。

C++
#include 
using namespace std;
/* implementation of strcmp that ignores cases */
int ic_strcmp(string s1, string s2) 
{ 
    int i; 
    for (i = 0; s1[i] && s2[i]; ++i) 
    { 
        /* If characters are same or inverting the 
        6th bit makes them same */
        if (s1[i] == s2[i] || (s1[i] ^ 32) == s2[i]) 
        continue; 
        else
        break; 
    } 
  
    /* Compare the last (or first mismatching in 
    case of not same) characters */
    if (s1[i] == s2[i]) 
        return 0; 
  
    // Set the 6th bit in both, then compare 
    if ((s1[i] | 32) < (s2[i] | 32)) 
        return -1; 
    return 1; 
} 
  
// Driver program to test above function 
int main() 
{ 
    cout<<"ret: "<


C
#include 
  
/* implementation of strcmp that ignores cases */
int ic_strcmp(char *s1, char *s2)
{
    int i;
    for (i = 0; s1[i] && s2[i]; ++i)
    {
        /* If characters are same or inverting the 
           6th bit makes them same */
        if (s1[i] == s2[i] || (s1[i] ^ 32) == s2[i])
           continue;
        else
           break;
    }
  
    /* Compare the last (or first mismatching in 
       case of not same) characters */
    if (s1[i] == s2[i])
        return 0;
  
    // Set the 6th bit in both, then compare
    if ((s1[i] | 32) < (s2[i] | 32)) 
        return -1;
    return 1;
}
  
// Driver program to test above function
int main(void)
{
    printf("ret: %d\n", ic_strcmp("Geeks", "apple"));
    printf("ret: %d\n", ic_strcmp("", "ABCD"));
    printf("ret: %d\n", ic_strcmp("ABCD", "z"));
    printf("ret: %d\n", ic_strcmp("ABCD", "abcdEghe"));
    printf("ret: %d\n", ic_strcmp("GeeksForGeeks", "gEEksFORGeEKs"));
    printf("ret: %d\n", ic_strcmp("GeeksForGeeks", "geeksForGeeks"));
    return 0;
}


输出:

ret: 1
ret: -1
ret: -1
ret: -1
ret: 0
ret: 0