实验六
#include<stdio.h> #define N 4 int main() { int x[N] = { 1,9,8,4 }; int i; int* p; for (i = 0; i < N; i++) printf("%d", x[i]); printf("\n"); for (p = x; p < x + N; p++) printf("%d", *p); printf("\n"); p = x; for (i = 0; i < N; i++) printf("%d", *(p+i)); printf("\n"); p = x; for (i = 0; i < N; i++) printf("%d", p[i]); printf("\n"); return 0; }
#include<stdio.h> #define N 4 int main() { char x[N] = { '1','9','8','4' }; int i; char* p; for (i = 0; i < N; i++) printf("%c", x[i]); printf("\n"); for (p = x; p < x + N; p++) printf("%c", *p); printf("\n"); p = x; for (i = 0; i < N; i++) printf("%c", *(p + i)); printf("\n"); p = x; for (i = 0; i < N; i++) printf("%c", p[i]); printf("\n"); return 0; }
回答问题:1.2004;2.2001;3.因为整型占四个字节,字符型占一个字节。
#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"); } for (p = &x[0][0], i = 0; p < &x[0][0] + 8; p++, i++) { printf("%d", *p); if ((i + 1) % 4 == 0) printf("\n"); } for (q = x; q < x + 2; q++) { for (j = 0; j < 4; j++) printf("%d",*(*q+j)); printf("\n"); } return 0; }
#include<stdio.h> int main() { char x[2][4] = { {'1','9','8','4'},{'2','0','2','2'} }; int i, j; char* p; char(*q)[4]; for (i = 0; i < 2; i++) { for (j = 0; j < 4; j++) printf("%c", x[i][j]); printf("\n"); } for (p = &x[0][0], i = 0; p < &x[0][0] + 8; p++, i++) { printf("%c", *p); if ((i + 1) % 4 == 0) printf("\n"); } for (q = x; q < x + 2; q++) { for (j = 0; j < 4; j++) printf("%c", *(*q + j)); printf("\n"); } return 0; }
回答问题:1.2004;2016;
2.2001;2004;
3.因为首先,整型占4个字节,字符型占1个;并且q与p不同,q指向的是一维数组,进行++操作后,跳过的是一整个数组,而不是跳过一个元素。
#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; }
#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; 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; }
回答问题:实验3.1:1.大小是13;计算的是数组s1的大小;统计的是数组s1中的有效字符;
2.不能;
3.交换了。
实验3.2:1.存放的是字符串的首地址;计算的是地址变量s1所占的字节数;统计的是所有有效字符的个数;
2.可以;
3.交换的是地址;在内存存储单元中没有交换。
#include<stdio.h> #include<string.h> #define N 5 int check_id(char* str); int main() { char* pid[N] = { "31010120000721656X", "330106199609203301", "53010220051126571", "510104199211197977", "53010220051126133Y" }; int i; for (i = 0; i < N; i++) if (check_id(pid[i])) printf("%s\tTrue\n", pid[i]); else printf("%s\tFalse\n", pid[i]); return 0; } int check_id(char* str) { int i; if (strlen(str) != 18) return 0; for (i = 0; i < 18; i++) { if ((str[i] >= '0' && str[i] <= '9') || str[i] == 'X') continue; else return 0; } return 1; }
#include<stdio.h> #include<string.h> #define N 80 int is_palindrome(char* s); int main() { char str[N]; int flag; printf("Enter a string:\n"); gets_s(str); flag = is_palindrome(str); if (flag) printf("YES\n"); else printf("NO\n"); return 0; } int is_palindrome(char* s) { int i,j; j = strlen(s); for (i = 0;s[i]!='\0'; i++) { if (s[i] == s[j - i-1]) continue; else return 0; } return 1; }
#include<stdio.h> #define N 80 void encoder(char* s); void decoder(char* s); int main() { char words[N]; printf("输入英文文本: "); gets_s(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=0; for (i = 0; s[i] != '\0'; i++) j++; for (i = 0; i < j; i++) { if ((s[i] >= 'a' && s[i] < 'z') || (s[i] >= 'A' && s[i] < 'Z')) s[i] = s[i] + 1; else if ((s[i] == 'z') || (s[i] == 'Z')) s[i] = s[i] - 25; } } void decoder(char* s) { int i, j = 0; for (i = 0; s[i] != '\0'; i++) j++; for (i = 0; i < j; i++) { if ((s[i] > 'a' && s[i] <= 'z') || (s[i] > 'A' && s[i] <= 'Z')) s[i] = s[i] - 1; else if ((s[i] == 'a') || (s[i] == 'A')) s[i] = s[i] + 25; } }