shiyan6

#include <stdio.h>
#define N 4
int main()
{
int x[N] = {1, 9, 8, 4};
int i;
int *p;

for(p=x; p<x+N; ++p)
printf("%d", *p);
printf("\n");

return 0;

}
2004
2001

#include <stdio.h>
#define N 4
int main()
{char x[N] = {'1', '9', '8', '4'};
int i;
char *p;
for(p=x; p<x+N; ++p)
printf("%c", *p);
printf("\n");
return 0;
}
int 类型所占字节4；char 类型占1节

 

#include <stdio.h>
int main()
{
int x[2][4] = { {1,9,8,4}, {2,0,2,2}} ;
int i, j;
int *p; 
int (*q)[4];
for(i=0; i<2; ++i)
{
for(j=0; j<4; ++j)
printf("%d", x[i][j]);
printf("\n");
}
return 0;
}

#include<stdio.h>
int main()
{
    int x[2][4] = { {'1', '9', '8', '4'}, {'2', '0', '2', '2'} };
    int i, j;
    int* p;
    int(*q)[4];
    for (p = &x[0][0], i = 0; p < &x[0][0] + 8; ++p, ++i)
    {
        printf("%c", *p);
        if ((i + 1) % 4 == 0)
            printf("\n");
    }

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<string.h>
#define N 80
int main()
{
    char s1[] = "c,i love u.";
    char s2[] = "c,i hate u.";
    char tmp[N];
    printf("sizeof(s1)vs.strlen(s1):\n");
    printf("sizeof(s1)=%d\n", sizeof(s1));
    printf("strlen(s1)=%d\n", strlen(s1));
    printf("\nbefore swap: \n");
    printf("s1: %s\n", s1);
    printf("s2: %s\n", s2);
    printf("\nswapping...\n");
    strcpy(tmp, s1);
    strcpy(s1, s2);
    strcpy(s2, tmp);
    printf("\nafter swap: \n");
    printf("s1: %s\n", s1);
    printf("s2: %s\n", s2);
    return 0;
}

#include<stdio.h>
#include<string.h>
#define N 80
int main()
{
    char* s1;
    s1 = "C, I love u.";
    char* s2 = "C, I hate u.";
    char* tmp;
    printf("sizeof(s1) vs. strlen(s1): \n");
    printf("sizeof(s1) = %d\n", sizeof(s1));
    printf("strlen(s1) = %d\n", strlen(s1));
    printf("\nbefore swap: \n");
    printf("s1: %s\n", s1);
    printf("s2: %s\n", s2);
    printf("\nswapping...\n");
    tmp = s1;
    s1 = s2;
    s2 = tmp;
    printf("\nafter swap: \n");
    printf("s1: %s\n", s1);
    printf("s2: %s\n", s2);
    return 0;
}
sizeof是数据类型占内存的大小，strlen是字符串的大小
不能

#include<stdio.h>
#include<string.h>
#define N 5
int check_id(char* str);
int main()
{
    char *pid[N]= 
    { "31010120000721656X",
"330106199609203301",
"53010220051126571",
"510104199211173977",
"53010220051126133Y" };
    int i;
    for (i = 0; i < N; ++i)
        if (check_id(pid[i]))
            printf("%s\tTure\n", pid[i]);
        else
            printf("%s\tFalse\n", pid[i]);
    return 0;
}
int check_id(char* str)
{
    int k;
    for (k = 0;*(str+k)!=0; k++)
    {
        if (  *(str+k)=='X' || '0' <= *(str + k) && *(str + k) <= '9')
        
            continue;
        else
            return 0;
    }
    if (k == 18)
        return 1;
    else
        return 0;
}
交换的是地址，没有交换

#include<stdio.h>
#include<string.h>
#define N 80
int is_pailindrome(char* s);
int main()
{
    char str[N];
    int flag;
    printf("Enter a string:\n");
    while(gets(str)!=0)
    {flag = is_palindrome(str);
    if (flag)
        printf("YES\n");
    else
        printf("NO\n"); }
    return 0;
}
int is_palindrome(char* s)
{
    int i, j, m;
    m = strlen(s)-1;
    for (i = 0; i <= m / 2; i++)
    {
        if (*(s + i) == *(s + m - i )|| *(s + i)+32 == *(s + m - i))
            continue;
        else
            return 0;
    }
    if (i = m / 2)
        return 1;
}

#include<stdio.h>
#include<string.h>
#define N 80
void encoder(char* s);
void decoder(char* s);
int main()
{
    char words[N];
    printf("输入文本：");
    gets(words);
    printf("编码后的英文文本：");
    encoder(words);
    printf("%s\n", words);
    printf("对编码后的英文文本解码：");
    decoder(words);
    printf("%s\n", words);
    return 0;
}
void encoder(char* s)
{
    int i, j, k;
    j = strlen(s);
    for (i = 0; i <= j; i++)
    {
        if (*(s + i) >= 'A' && *(s + i) < 'Z' || *(s + i) >= 'a' && *(s + i) < 'z')
        {
            *(s + i) = *(s + i) + 1;
            continue;
        }
        if (*(s + i) == 'Z')
            *(s + i) = 'A';
        if (*(s + i) == 'z')
            *(s + i) = 'a';
    }
    *(s + j) = 0;
}
void decoder(char* s)
{
    int i, j;
    j = strlen(s);
        for (i = 0; i < j; i++)
        {
            if (*(s + i) > 'A' && *(s + i) <= 'Z' || *(s + i) >= 'a' && *(s + i) <= 'z')
            {
                *(s + i) = *(s + i) - 1;
                continue;
            }
            if (*(s + i) == 'A')
                *(s + i) = 'Z';
            if (*(s + i) == 'a')
                *(s + i) = 'z';
        }
        *(s + j) = 0;
}