String processing 2-strcat/strcmp/strcpy/strchr/strrchr/strstr

Strcat

A simple strcat, I in the actual coding, or found the problem, first list

1. Mainly in Strcat_m, the beginning of Line8,while (tmp++!= ' ") and the following line9 is not the same.

Line8: After TMP points to ' "," and then shift back to a unit, so the last TMP point to ' the "after a unit

Line9: This is the right point to the ' yes '

2. In Line13, if you need to strcat_m many times, such as

c = strcat_m (a,b);

c = strcat_m (c,d);

The return--tmp will directly point to the last character, so it is convenient to continue the strcat and no longer need to traverse strdest to ' "and more efficiently.

#include <stdio.h>
#include <assert.h>

char* strcat_m (char* strdest, const char* STRSRC)
{
      assert (strdest!= null && strsrc!= null);
      char *tmp = strdest;
      while (*tmp++!= ' ");
      while (*tmp!= ' ")
          tmp++;
      while (*strsrc!= ' ")
          *tmp++ = *strsrc++;
      return--tmp;
      return strdest;
}
void main (void)
{
    char *buffer;
    Char str[100]  = "Hello";
    char* str1 = "World";
    Buffer = Strcat_m (STR,STR1);
    printf ("%s\n", buffer);
}

strcmp

#include <stdio.h>

int strcmp (const char* str1, const char* str2)
{
    int ret=0;
    while (!) ( ret= (*str1-*str2)) && *str1 && *str2)
    {
        str1++;
        str2++;
    }
    if (ret<0)
        return-1;
    else if (ret >0) return
        1;
    else return
        ret;
}
int main (void)
{
    char* p;
    char* str1 = "Hello";
    char* str2 = "Hellohe";
    printf ("%d\n", strcmp (STR1,STR2));
}

strcmp Another way of writing, considering the word length of case insensitive and CMP, which is actually the original form of Android.

int strncmp (char* s1, const char* s2, int n)
{
    assert (S1!= null && s2!= null);
    char tmp_s1,tmp_s2;
    int index=0;
    do{
        if ((tmp_s1 = *s1++) >= ' a ' && (tmp_s1 <= ' Z '))
            tmp_s1-= ' a '-' a ';
        if ((Tmp_s2 = *s2++) >= ' a ' && (tmp_s2 <= ' Z '))
            tmp_s2-= ' a '-' a ';
        index++;

    } while ((TMP_S1==TMP_S2) && tmp_s1 && index<n);
    return tmp_s1-tmp_s2;
}

strcpy

item1---->*dest = ' "; can return string or no return

ITEM2---->dest string must have a place to save, if there is no malloc, the program error

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <windows.h >
#include <assert.h>

void strcpy (char *dest,const char* src)
{
	assert (src!= NULL);
	while (*src!= ' ")
		*dest++ = *src++;
	*dest = ' i ';
}

int main (int argc, char* argv[])
{
	char *p = "Helloword";
	Char *q = (char *) malloc (a);
	strcpy (q,p);
	printf ("%s\n", q);

	return 0;
}

STRRCHR:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <windows.h >
#include <assert.h>

char *my_strrchr (char* p, char h)
{
	assert (p!=null);
	char *tmp=null;
	while (*p!= ' ") {
		if (*p = h)
			tmp = p;
		p++;
	}
	
	return tmp;
}

int main (int argc, char* argv[])
{
	char *p = "HelloWorld";
	Char *cout = MY_STRRCHR (P, ' l ');

	printf ("%s\n", cout);

	return 0;
}

STRCHR:

* * Plus a case-sensitivity judgment

Char *my_strchr (char* p, char h)
{
	assert (p!=null);

	if (h>= ' a ' && h<= ' Z ')
		h = n ' a ' + ' a ';

	while (*p!= ')
	{
		if (*p = = H | | (*p-' a ' + ' a ') = = h) return
			p;
		else
			p++;
	}

	if (*p = = ' = ') return
		NULL;
}

STRSTR:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <windows.h >
#include <assert.h>

char *my_strstr (char* p1, char* p2)
{
	assert (P1!=null && p2!= NULL);
	
	for (; *p1!= ';p 1++)
	{
		char *tmp_p1=p1;
		char *tmp_p2=p2;
		while (*tmp_p2!= ' && *tmp_p1!= ') {
			if (*tmp_p1 = = *tmp_p2) {
				tmp_p1++;
				tmp_p2++;
			}
			else break
				;
		}
		if (*tmp_p2 = = ' ") return
			p1
	}
	return NULL;
}

int main (int argc, char* argv[])
{
	char *p = "HelloWorld";
	Char *q = "Llo";
	Char *cout = MY_STRSTR (p,q);
	
	printf ("%s\n", cout);
	return 0;
}