Reverse the contents of str in a string and output

Basic knowledge:

1. The reading rules of scanf have "default read to the end of the space"

Solution: scanf("% [^\n] ", arr); Function: " read to end of newline "

2. Commonly used gets and puts for strings

gets() reads a string including spaces

put(x) is equivalent to printf(" %s \n ", x)     will have one more newline than normal printf

3. The difference between character arrays and strings (with or without \0)

例1：char s1[3]={'a'，'b'，'c'}，s2[4]={'a','b','c','0'};

Both s1 and s2 are character arrays, but s2 is also a string .

4. Initialization rules:

char str[1000]=''abdce'' --------Add \0 after default (namely string )

5. Two ways of printing character arrays (1. traversing %c 2. Printing %s   directly)

example:

#include<stdio.h>
int main()
{
	char arr1[4], arr2[5];
	scanf("%s", arr1);//&arr1[]
	//方式1(一个一个出来）
	int i = 0;
	for (i = 0; i < 4; i++)
	{
		printf("%c", arr1[i]);
	}
	printf("\n");
	//方式2(一整个出来）
	printf("%s", arr1);
}

Output result:

———————————————————————————————————————————

Topic: Reverse the contents of a string str

#include<stdio.h>
#include<string.h>
int main()
{
	char arr1[10000] = { 0 };
	scanf("%[^\n]", arr1);
	int len = strlen(arr1);
	int left = 0;
	int right = len - 1;
	while (left < right)
	{
		char tmp = arr1[left];
		arr1[left] = arr1[right];
		arr1[right] = tmp;
		left++;
		right--;
	}
	printf("%s\n", arr1);
	return 0;
}