实验五
#include<stdio.h> #define N 5 void input(int x[],int n); void output(int x[],int n); void find_min_max(int x[],int n,int*pmin,int*pmax); int main(){ int a[N]; int min,max; printf("录入%d个数据：\n",N); input(a,N); printf("数据是：\n"); output(a,N); printf("数据处理...\n"); find_min_max(a,N,&min,&max); printf("输出结果：\n"); printf("min=%d,max=%d\n",min,max); return 0; } void input(int x[],int n){ int i; for(i=0;i<n;++i) scanf("%d",&x[i]); } void output(int x[],int n){ int i; for(i=0;i<n;++i) printf("%d ",x[i]); printf("\n"); } void find_min_max(int x[],int n,int *pmin,int *pmax){ int i; *pmin=*pmax=x[0]; for(i=0;i<n;++i) if(x[i]<*pmin) *pmin=x[i]; else if(x[i]>*pmax) *pmax=x[i]; }
1.find_min_max功能找出数组中的最大值和最小值
2.pmin,pmax都指向x[0]的地址
#include <stdio.h> #define N 5 void input(int x[], int n); void output(int x[], int n); int *find_max(int x[], int n); int main() { int a[N]; int *pmax; printf("录入%d个数据:\n", N); input(a, N); printf("数据是: \n"); output(a, N); printf("数据处理...\n"); pmax = find_max(a, N); printf("输出结果:\n"); printf("max = %d\n", *pmax); return 0; } void input(int x[], int n) { int i; for(i = 0; i < n; ++i) scanf("%d", &x[i]); } void output(int x[], int n) { int i; for(i = 0; i < n; ++i) printf("%d ", x[i]); printf("\n"); } int *find_max(int x[], int n) { int max_index = 0; int i; for(i = 0; i < n; ++i) if(x[i] > x[max_index]) max_index = i; return &x[max_index]; }
1.find_max功能找出数组中的最大值返回最大值的地址
2.不可以，指针变量未指向地址
#include <stdio.h> #include <string.h> #define N 80 int main() { char s1[N] = "Learning makes me happy"; char s2[N] = "Learning makes me sleepy"; 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; }
1.s1大小为80；sizeof(s1)计算的是数组所占地址大小；strlen(s1)统计数组元素数量
2.不能，s1表示地址，不能直接赋值
3.交换了
#include <stdio.h> #include <string.h> #define N 80 int main() { char *s1 = "Learning makes me happy"; char *s2 = "Learning makes me sleepy"; 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; }
s1存放字符串“Learning makes me happy",sizeof(s1)计算s1本身大小，strlen（s1）计算s1指向的字符串长度
可以，原代码在声明时就进行初始化，改后是先声明再赋值
交换s1和s2指向的地址，字符串在内存中没交换
#include <stdio.h> int main() { int x[2][4] = {{1, 9, 8, 4}, {2, 0, 4, 9}}; int i, j; int *ptr1; int(*ptr2)[4]; printf("输出1: 使用数组名、下标直接访问二维数组元素\n"); for (i = 0; i < 2; ++i) { for (j = 0; j < 4; ++j) printf("%d ", x[i][j]); printf("\n"); } printf("\n输出2: 使用指针变量ptr1(指向元素)间接访问\n"); for (ptr1 = &x[0][0], i = 0; ptr1 < &x[0][0] + 8; ++ptr1, ++i) { printf("%d ", *ptr1); if ((i + 1) % 4 == 0) printf("\n"); } printf("\n输出3: 使用指针变量ptr2(指向一维数组)间接访问\n"); for (ptr2 = x; ptr2 < x + 2; ++ptr2) { for (j = 0; j < 4; ++j) printf("%d ", *(*ptr2 + j)); printf("\n"); } return 0; }
#include <stdio.h> #define N 80 void replace(char *str, char old_char, char new_char); int main() { char text[N] = "Programming is difficult or not, it is a question."; printf("原始文本: \n"); printf("%s\n", text); replace(text, 'i', '*'); printf("处理后文本: \n"); printf("%s\n", text); return 0; } void replace(char *str, char old_char, char new_char) { int i; while(*str) { if(*str == old_char) *str = new_char; str++; } }
函数作用将字符串中原有的字符替换成新字符
可以
#include <stdio.h> #define N 80 char *str_trunc(char *str, char x); int main() { char str[N]; char ch; while(printf("输入字符串: "), gets(str) != NULL) { printf("输入一个字符: "); ch = getchar(); printf("截断处理...\n"); str_trunc(str, ch); printf("截断处理后的字符串: %s\n\n", str); getchar(); } return 0; } char *str_trunc(char *str,char x){ while(*str){ if(*str==x) *str=0; else *str++; } return *str; }
line18作用去除空格干扰
#include <stdio.h> #include <string.h> #define N 5 int check_id(char* str); // 函数声明 int main() { char* pid[N] = { "31010120000721656X", "3301061996X0203301", "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 count = 0; while (*str) { count++; if (*str < 48 || *str > 57) { if (*str != 'X' || count != 18) { return 0; } } str++; } if (count != 18) { return 0; } return 1; }
#include <stdio.h> #define N 80 void encoder(char* str, int n); void decoder(char* str, int n); int main() { char words[N]; int n; printf("输入英文文本: "); gets(words); printf("输入n: "); scanf("%d", &n); printf("编码后的英文文本: "); encoder(words, n); printf("%s\n", words); printf("对编码后的英文文本解码: "); decoder(words, n); printf("%s\n", words); return 0; } void encoder(char* str, int n) { while (*str) { if (*str >= 'A' && *str <= 'Z') { *str = (*str - 'A' + n % 26 + 26) % 26 + 'A'; } else if (*str >= 'a' && *str <= 'z') { *str = (*str - 'a' + n % 26 + 26) % 26 + 'a'; } str++; } } void decoder(char* str, int n) { while (*str) { if (*str >= 'A' && *str <= 'Z') { *str = (*str - 'A' + 26 - n % 26) % 26 + 'A'; } else if (*str >= 'a' && *str <= 'z') { *str = (*str - 'a' + 26 - n % 26) % 26 + 'a'; } str++; } }
#include <stdio.h> #include <string.h> int main(int argc, char *argv[]) { int i,j; char* temp; for(i = 1; i < argc; i++){ for(j=1;j<argc-i;j++){ if(strcmp(argv[j],argv[j+1])>0){ temp = argv[j]; argv[j] = argv[j+1]; argv[j+1] = temp; } } } for(i = 1; i < argc; ++i) printf("hello, %s\n", argv[i]); return 0; }
