Write strcmp () function by yourself

I found a library function strcmp () source code on the Internet:

int strcmp (const char * src, const char * dst){        int ret = 0 ;        while( ! (ret = *(unsigned char *)src - *(unsigned char *)dst) && *dst)                ++src, ++dst;          if ( ret < 0 )                ret = -1 ;        else if ( ret > 0 )                ret = 1 ;        return( ret );}

I initially wrote:

int strcmp(char const *s1, char const *s2){int i = 0;while(1) {if(s1[i] == '\0' && s2[i] == '\0')return 0;else if(s1[i] > s2[i])return 1;else if(s1[i] < s2[i])return -1;i++;}} 

Then we can streamline the process as follows:

int strcmp(char const *s1, char const *s2){int ret, i = 0;while(1) {ret = s1[i] - s2[i];if(ret || !s1[i] || !s2[i])return ret;i++;}} 

Continue to streamline:

Int strcmp (char const * S1, char const * S2) {int ret, I = 0; while (1) {ret = S1 [I]-S2 [I]; if (Ret |! S1 [I]) // as long as one of the strings encounters \ 0, RET will not be zero. return ret; I ++ ;}}

However, if the input pointer is null, it will crash, and the improvement is as follows:

Int strcmp (char const * S1, char const * S2) {int ret, I = 0; If (! S1 |! S2) return S1-S2; while (1) {ret = S1 [I]-S2 [I]; If (Ret |! S1 [I]) // as long as one of the strings encounters \ 0, RET will not be zero. return ret; I ++ ;}}

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