2021-08-10 character pointer

1. The string is left-handed

Implement a function , You can rotate left in a string k Characters .

for example ：

ABCD Turn a character left to get BCDA

ABCD Two left-handed characters get CDAB

analysis : Let's first consider the left rotation of a character and then proceed for Cycle the number of left turns that meet the requirements of the topic , First put the characters ‘A’ Save up , And then 'BCD‘ Move forward one by one , Finally, the ’A‘ Put it in the last place to meet the condition , Let's do the following .

The code is as follows ：

void my_leftmove(char* arr, int m)
{
	int len = strlen(arr);
	int i,j;
	for (i = 0; i < m; i++)
	{
		// Rotate one character 
		//1. Save the first character 
		char p = *arr;
		//2. Move the following characters forward in turn 
		for (j = 0; j < len - 1; j++){
			*(arr + j) = *(arr + j + 1);
	}
		//3. Put the saved characters in the last place 
		*(arr + len - 1) = p;
	}
}
int main()
{
	char arr[] = "ABCD";
	int k;
	scanf("%d", &k);
	my_leftmove(arr, k);
	printf("%s", arr);
	return 0;
}

2.

String rotation result

Write a function , To determine whether a string is the rotated string of another string .

for example ： Given s1 =AABCD and s2 = BCDAA, return 1

Given s1=abcd and s2=ACBD, return 0.

AABCD Turn a character left to get ABCDA

AABCD Two left-handed characters get BCDAA

AABCD Turn one character right to get DAABC

Code 1 as follows ：

#include<stdio.h>
void my_leftmove(char* arr, int m)
{
	int len = strlen(arr);
	int i,j;
	for (i = 0; i < m; i++)
	{
		// Rotate one character 
		//1. Save the first character 
		char p = *arr;
		//2. Move the following characters forward in turn 
		for (j = 0; j < len - 1; j++){
			*(arr + j) = *(arr + j + 1);
	}
		//3. Put the saved characters in the last place 
		*(arr + len - 1) = p;
	}
}

int  is_moveleft(char a1[], char a2[])
{
	int len1= strlen(a1);
	int len2 = strlen(a2);
	// First determine whether the string length is equal , If it is not equal, it will return to ;
	if (len1 != len2) {
		return 0;
	}
	int i=0;
	for (i = 0; i < len1; i++) {
		// Shift string left 
		my_leftmove(a1, 1);
		// Compare whether two arrays are equal ;
		if (strcmp(a1, a2) == 0) {
			return 1;
		}
	}
	return 0;
}
int main()
{
	char a1[] = "ABCDE";
	char a2[] = "BCD";
	int ret = is_moveleft(a1,a2);
	if (ret == 1) {
		printf("YES\n");
	}
	else {
		printf("NO\n");
	}
	return 0;
}

Code 2 as follows ：

#include<stdio.h>
#include<assert.h>
#include<assert.h>
int is_moveleft(char a1[], char a2[]) {
	// Determine whether it is null 
	assert(a1);
	assert(a2);
	int len1 = strlen(a1);
	int len2 = strlen(a2);
	if (len1 != len2) {
		return 0;
	}
	int i = 0;
	// to a1 Add a... To the back a1 String 
	strncat(a1, a1, len1);
	// Judge a2 Whether it is a1 String 
	if (NULL == strstr(a1, a2)) {
		return 0;
	}
	else {
		return 1;
	}
}
int main()
{
	char a1[] = "ABCDE";
	char a2[] = "BCDEA";
	int ret = is_moveleft(a1,a2);
	if (ret == 1) {
		printf("YES\n");
	}
	else {
		printf("NO\n");
	}
	return 0;
}