7.29 二维数组 malloc 外挂 实现库函数

#include <stdio.h>
#include <string.h>
void init(int a[][6] ,int m, int n)
{
        printf("%d\n",(int)sizeof(a)); //结果是4
}
int main()
{
        int a[5][6];
        init(a,5,6);
}

#include <stdio.h>
#include <time.h>
#include <stdlib.h>
#define M 4
#define N 13
int main()
{
        char a[M][N] = {0};
        srand(time(NULL));
        int n,m,num;
        const char X[] = {‘1‘,‘2‘,‘3‘,‘4‘,‘5‘,‘6‘,‘7‘,‘8‘,‘9‘,‘t‘,‘j‘,‘q‘,‘k‘};
        const char Y[] = {‘a‘,‘b‘,‘c‘,‘d‘};
        printf("请输入你现在还有几张牌：");
        scanf("%d",&num);
        while(num>0)
        {
                m = rand()%4;
                n = rand()%13;
                if(!a[m][n])
                {
                        a[m][n] = 1;
                        num--;
                        printf("%c %c\n",Y[m],X[n]);
                }
        }
        return 0;
}

#include <stdio.h>
#include <stdlib.h>
int main()
{
        int n;
        printf("你的名字最多多长:");
        scanf("%d", &n);
        getchar(); //过滤回车
        char * a;
        a = (char *)malloc(n * sizeof(char));
        printf("请输入你的名字:");
        gets(a);
        printf("%s\n", a);
        free(a);
}

#include <stdio.h>
#include <string.h>
char * str_reverse(char * str)
{
        char temp;
        int len = strlen(str),i;
        for (i = 0; i < len/2; i++)
        {
                temp = str[i];
                str[i] = str[len-i-1];
                str[len-i-1] = temp;
        }
        return str;
}
int main()
{
        char s[100] = "hello";
        char * p = str_reverse(s);
        printf("%s\n",p);
}

#include <stdio.h>
#include <string.h>
int str_times(char * str,char ch)
{
        int i = 0;
        while(*str != ‘\0‘)
        {
                if (*str == ch)
                        i++;
                str++;
        }
        return i;
}
int main()
{
        char s[100] = "hello";
        printf("%d\n",str_times( s , ‘l‘));
}

sizt_t strlen(const char *s)
{
    size_t n = 0;
    while(*s++)
            n++;
    return n;
}

sizt_t strlen(const char *s)
{
    const char * p = s;
    while(*s)
           s++
    return s - p;
}

#include <stdio.h>
#include <string.h>
char * str_find(char * str, char * f)
{
        while (*str)
        {
                char * a = str;
                char * b = f;
                char * res = NULL;
                if (*a == *b)
                {
                        res = a;
                        while (*++a == *++b ) ;
                        if (*b == ‘\0‘)
                                return res;
                }
                str++;
        }
        return NULL;
}
int main()
{
        char *s = "helloworld";
        printf("%s\n",str_find(s ,"lo"));
        return 0;
}

#include <stdio.h>
#include <string.h>
void str_cpy( char * dest , const char * src)
{
    while(*dest++ = *src++);
}
int main()
{
    char buf[100] = "aaaaaaaaaaaaaaaaaaaaaaaa";;
    str_cpy(buf , "liuwei");
    printf("%s\n" , buf);
    return 0;
}

#include <stdio.h>
#include <string.h>
char * str_cat(char *p,char *s)
{
        char * bak = p;
        while(*p)
        {
                p++;
        }
        while(*p++ = *s++)
        {
        }
        return bak;
}
int main()
{
        char s[10] = "hello";
        char v[10] = "world";
        printf("%s\n",str_cat(s,v));
        return 0;
}