1、小型数据库
1 #include <stdio.h> 2 #include <stdlib.h> 3 #define N 100 4 5 struct student{ 6 int no; 7 char name[12]; 8 int score; 9 }s[N]; 10 11 int main() 12 { 13 int n; 14 scanf("%d",&n); 15 /* 保存 */ 16 FILE *fp; 17 fp = fopen("DATA5614.DB","wb"); 18 scanf("%d%s%d", &s[0].no,s[0].name,&s[0].score); 19 fprintf(fp,"%d %s %d ", s[0].no,s[0].name,s[0].score); 20 int max = s[0].score, index = 0; 21 for(int i=1; i<n; ++i) 22 { 23 scanf("%d%s%d", &s[i].no,s[i].name,&s[i].score); 24 fprintf(fp,"%d %s %d ", s[i].no,s[i].name,s[i].score); 25 if(s[i].score>max){ 26 max = s[i].score; 27 index = i; 28 } 29 } 30 /* rewind */ 31 rewind(fp); 32 /*读取 */ 33 fp = fopen("DATA5614.DB","rb"); 34 struct student stu; 35 for(int i=0; i<=index; ++i) 36 { 37 fscanf(fp,"%d%s%d", &stu.no,stu.name,&stu.score); 38 } 39 printf("%d %s %d", stu.no,stu.name,stu.score); 40 fclose(fp); 41 return 0; 42 }
2、检查图像文件格式
1 #include <stdio.h> 2 #include <stdlib.h> 3 #include <string.h> 4 5 int main() 6 { 7 char arr[100]=""; 8 char JFIF[]="JFIF"; //6 9 char GIF89a[]="GIF89a";//0 10 char PNG[]="PNG";//1 11 12 FILE *fp; 13 fp = fopen("DATA5609.DAT","rb"); 14 fread(arr,sizeof(unsigned char),100,fp); 15 /* */ 16 if(0 == strncmp(&arr[6],JFIF,4)) 17 printf("%s ",JFIF); 18 else if(0 == strncmp(&arr[0],GIF89a,6)) 19 printf("%s ",GIF89a); 20 else if(0 == strncmp(&arr[1],PNG,3)) 21 printf("%s ",PNG); 22 else 23 printf("NULL "); 24 fclose(fp); 25 return 0; 26 }
3、重组字符串
1 #include<stdio.h> 2 #include <string.h> 3 #define N 100 4 void fun(char *s, char *t); 5 int main() 6 { 7 char s[N] = "", t[N] = ""; 8 gets(s); 9 fun(s,t); 10 printf("%s",t); 11 return 0; 12 } 13 void fun(char *s, char *t){ 14 int index = 0; 15 for(int i=0; s[i]; ++i){ 16 if(i%2&&s[i]%2) 17 t[index++] = s[i]; 18 } 19 t[index] = ' '; 20 }
4、分数加减法
1 #include<stdio.h> 2 #include <string.h> 3 #define N 100 4 void fun(int *num,int *den); 5 int main() 6 { 7 char s[N] = ""; 8 gets(s); 9 10 int a,b,c,d,num,den; 11 a=s[2]-'0',b=s[0]-'0',c=s[4]-'0',d=s[6]-'0'; 12 if(s[3]=='+')num=b*d+c*a; 13 if(s[3]=='-')num=b*d-c*a; 14 den=a*d; 15 if(!num) printf("0"); 16 else{ 17 fun(&num,&den); 18 printf("%d/%d",num,den); 19 } 20 return 0; 21 } 22 void fun(int *num,int *den){ 23 int t = *num>*den?*num:*den; 24 while(t) 25 { 26 if((*num)%t==0&&(*den)%t==0){ 27 *num /= t; 28 *den /= t; 29 break; 30 } 31 t--; 32 } 33 }
5、搜索字符
1 #include<stdio.h> 2 #include <string.h> 3 #define N 100 4 char* search(char *cpsource, char ch); 5 int main() 6 { 7 char s[N] = "",ch; 8 gets(s); 9 ch = getchar(); 10 printf("%s",search(s,ch)); 11 return 0; 12 } 13 char* search(char *cpsource, char ch){ 14 int index=0, count=0, max=0; 15 for(int i=0; cpsource[i]; ++i){ 16 if(cpsource[i]==ch){ 17 count++; 18 } 19 else{ 20 if(max<count){ 21 max = count; 22 index = i-max; 23 } 24 count=0; 25 } 26 } 27 cpsource[index+max] = ' '; 28 return &cpsource[index]; 29 }
6、复数
1 #include<stdio.h> 2 #include <string.h> 3 #define N 100 4 typedef struct complex{ 5 double r; 6 double i; 7 }COMPLEX; 8 9 int main() 10 { /* 1 */ 11 COMPLEX c[2]; 12 double r,i; 13 for(int i=0; i<2; ++i){ 14 scanf("%lf%lf",&c[i].r,&c[i].i); 15 } 16 /* 2 */ 17 char ch[5]="+-*/"; 18 for(int j=0; j<4; ++j){ 19 switch(ch[j]){ 20 case '+': 21 r=c[0].r+c[1].r; 22 i=c[0].i+c[1].i; 23 break; 24 case '-': 25 r=c[0].r-c[1].r; 26 i=c[0].i-c[1].i; 27 break; 28 case '*': /* (ac-bd)+(bc+ad)i */ 29 r=c[0].r*c[1].r - c[0].i*c[1].i; 30 i=c[0].i*c[1].r + c[0].r*c[1].i; 31 break; 32 case '/': /*(ac+bd)/(c*c+d*d) +((bc-ad)/(c*c+d*d))i*/ 33 if(c[1].r||c[1].i){ 34 r=(c[0].r*c[1].r + c[0].i*c[1].i) 35 /(c[1].r*c[1].r+c[1].i*c[1].i); 36 i=(c[0].i*c[1].r - c[0].r*c[1].i) 37 /(c[1].r*c[1].r+c[1].i*c[1].i); 38 } 39 else { 40 r=i=0; 41 } 42 break; 43 } 44 printf("(%.2f+%.2fi)%c(%.2f+%.2fi)=(%.2f%+.2fi) ", 45 c[0].r,c[0].i,ch[j],c[1].r,c[1].i,r,i); 46 } 47 return 0; 48 }
7、插入字符
1 #include<stdio.h> 2 #include <string.h> 3 #define N 100 4 5 int main() 6 { 7 char s[N] = "", x; 8 int i; 9 gets(s); 10 scanf(" %c%d",&x,&i); 11 12 char t[N] = ""; 13 strncpy(t,s,i); 14 t[i] = x; 15 strcat(t,&s[i]); 16 puts(t); 17 return 0; 18 }
8、文件比较
1 #include <stdio.h> 2 #include <stdlib.h> 3 #include <string.h> 4 5 int main() 6 { 7 char str1[256]=""; 8 char str2[256]=""; 9 FILE *fp1,*fp2; 10 fp1 = fopen("DATA5613.TXT","r"); 11 fp2 = fopen("DATA5613.CPP","r"); 12 /* */ 13 int i,j; 14 for(i=0; !feof(fp1)&&!feof(fp2); ++i) 15 { 16 fgets(str1,sizeof(str1)-1,fp1); 17 fgets(str2,sizeof(str2)-1,fp2); 18 int flag = 0; 19 for(j=0; str1[j]&&str2[j]; ++j) 20 { 21 if(str1[j]!=str2[j]){ 22 flag = 1; 23 break; 24 } 25 } 26 if(flag) 27 printf("%d %d ",i+1,j+1); 28 } 29 /* */ 30 fclose(fp1); 31 fclose(fp2); 32 return 0; 33 }
9、检测位图长宽
1 #include <stdio.h> 2 #include <stdlib.h> 3 #pragma pack(1)//结构体按1个字节对齐 3 4 typedef struct tagBITMAPFILEHEADER{//文件头 4 5 unsigned short bfType;//文件类型，固定为BM 5 6 unsigned int bfSize;//文件大小（字节） 6 7 unsigned short bfReserved1;//保留 7 8 unsigned short bfReserved2;//保留 8 9 unsigned int bfOffBits;//位图数据到文件头的偏移位置 9 10 }BITMAPFILEHEADER; 11 12 typedef struct tagBITMAPINFOHEADER{//位图信息头 11 13 unsigned int biSize;//位图信息头的长度 12 14 long biWidth;//位图的宽度，以像素为单位 13 15 long biHeight;//位图的高度，以像素为单位 14 16 unsigned short biPlanes;//位图的位面数 15 17 unsigned short biBitCount;//每个像素的位数 18 unsigned int biCompression;//数据压缩类型 17 19 unsigned int biSizeImage;//位图数据大小（字节） 18 20 long biXPelsPerMeter;//水平分辨率（像素/米） 19 21 long biYPelsPerMeter;//垂直分辨率（像素/米） 20 22 unsigned int biClrUsed;//位图使用的颜色数 21 23 unsigned int biClrImportant;//调色板规范 22 24 }BITMAPINFOHEADER; 25 26 int main() 27 { 28 BITMAPFILEHEADER bmfh; 29 BITMAPINFOHEADER bmih; 30 FILE *bmp; 31 //printf("%d,%d ",sizeof(BITMAPFILEHEADER),sizeof(BITMAPINFOHEADER)); 32 bmp=fopen("DATA5611.BMP","rb"); 33 if(bmp!=NULL) { 34 fread(&bmfh,sizeof(BITMAPFILEHEADER),1,bmp); 35 fread(&bmih,sizeof(BITMAPINFOHEADER),1,bmp); 36 //printf("位图宽=%d,高=%d ",bmih.biWidth,bmih.biHeight); 37 printf("%ld %ld ",bmih.biHeight,bmih.biWidth); 38 fclose(bmp); 39 } 40 return 0; 41 }
10、POJer的烦恼
1 #include<stdio.h> 2 #include <string.h> 3 #define N 100 4 5 int main() 6 { 7 long long n; 8 scanf("%lld",&n); 9 int num[N] = {0},index = 0; 10 while(n) 11 { 12 num[index++] = n%2; 13 n /= 2; 14 } 15 16 for(int i=index-1; i>=0; --i) 17 printf("%d",num[i]); 18 return 0; 19 }