01/09 隨堂練習及作業

注意:

進一步示範 gets() 與 puts()

#include <stdio.h> void main() { char str[] = "abcd"; char buf[100]; int i; for (i=0; i<10; i++) puts(str); scanf("%s", buf); printf("gets() read in [%s]\n", buf); gets(buf); printf("gets() read in [%s]\n", buf); }

由檔案中讀取 n 個數字, 排序後寫到新的檔案內 (rewind() 函式示範)

#include <stdio.h> #include <stdlib.h> void swap(int *, int *); void selectionSort(int, int []); void main() { int number, data, i; int *dataArray; FILE *infp, *outfp; infp = fopen("test36.dat", "r"); if (infp == 0) { printf("error in opening test36.dat!!\n"); exit(1); } number = 0; while (1) { if (fscanf(infp, "%d", &data)!=1) break; number += 1; printf("%d\n", data); } printf("number of lines = %d\n", number); dataArray = (int *) malloc(number * sizeof(int)); if (dataArray == 0) { printf("data allocation failure!\n"); fclose(infp); exit(1); } rewind(infp); for (i=0; i<number; i++) { fscanf(infp, "%d", &dataArray[i]); printf("%d\n", dataArray[i]); } fclose(infp); // sorting selectionSort(number, dataArray); // open new file and output all sorted numbers outfp = fopen("test36a.dat", "w"); if (outfp == 0) { printf("error in opening test36a.dat!!\n"); exit(1); } for (i=0; i<number; i++) fprintf(outfp, "%d\n", dataArray[i]); free(dataArray); fclose(outfp); } void selectionSort(int n, int data[]) { int i, j, min; for (j=0; j<n-1; j++) { min = j; for (i=j+1; i<n; i++) if (data[i]<data[min]) min = i; swap(&data[j], &data[min]); } } void swap(int *ptrX, int *ptrY) { int tmp; tmp = *ptrX; *ptrX = *ptrY; *ptrY = tmp; }

將上面程式以函式形式撰寫

#include <stdio.h> #include <stdlib.h> void swap(int *, int *); void selectionSort(int, int []); void readInput(int *, int **); void writeOutput(int , int []); void main() { int number; int *dataArray; readInput(&number, &dataArray); selectionSort(number, dataArray); writeOutput(number, dataArray); } void readInput(int *number, int **dataArray) { FILE *infp; int data, i; infp = fopen("test36.dat", "r"); if (infp == 0) { printf("error in opening test36.dat!!\n"); exit(1); } *number = 0; while (1) { if (fscanf(infp, "%d", &data)!=1) break; *number += 1; printf("%d\n", data); } printf("number of lines = %d\n", *number); *dataArray = (int *) malloc(*number * sizeof(int)); if (*dataArray == 0) { printf("data allocation failure!\n"); fclose(infp); exit(1); } rewind(infp); for (i=0; i<*number; i++) { fscanf(infp, "%d", &(*dataArray)[i]); printf("%d\n", (*dataArray)[i]); } fclose(infp); } void selectionSort(int n, int data[]) { int i, j, min; for (j=0; j<n-1; j++) { min = j; for (i=j+1; i<n; i++) if (data[i]<data[min]) min = i; swap(&data[j], &data[min]); } } void swap(int *ptrX, int *ptrY) { int tmp; tmp = *ptrX; *ptrX = *ptrY; *ptrY = tmp; } void writeOutput(int number, int dataArray[]) { FILE *outfp; int i; outfp = fopen("test36a.dat", "w"); if (outfp == 0) { printf("error in opening test36a.dat!!\n"); exit(1); } for (i=0; i<number; i++) fprintf(outfp, "%d\n", dataArray[i]); free(dataArray); fclose(outfp); }

將字串內容以顛倒過來的順序列印 (版本一:遞迴) (版本二:strrev())

#include <stdio.h> void reverse(char *sPtr); void main() { char str[] = "This is a string to be reversed!"; reverse(str); printf("\n"); puts(str); } void reverse(char *sPtr) { if ('\0' == sPtr[0]) return; else { reverse(&sPtr[1]); putchar(sPtr[0]); } }

#include <stdio.h> #include <string.h> void main() { char str[] = "This is a string to be reversed!"; strrev(str); puts(str); }

#include <stdio.h> void main() { char *buf = "1.234 test 5.678 2345"; double x1, x2; int data; char name[20]; sscanf(buf, "%lf %s %lf %d", &x1, name, &x2, &data); printf("x1=%lf\n", x1); printf("x2=%lf\n", x2); printf("name=%s\n", name); printf("data=%d\n", data); }

#include <stdio.h> #define LEN 81 void main() { FILE *fp; char buf[LEN]; double fdata; char name[20]; int idata; fp = fopen("test40.dat", "r"); while (1) { if (fgets(buf, LEN-1, fp)==NULL) break; sscanf(buf, "%lf %s %d", &fdata, name, &idata); printf("fdata=%lf\n", fdata); printf("name=%s\n", name); printf("idata=%d\n", idata); } fclose(fp); }

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製作日期: 01/09/2003 by 丁培毅 (Pei-yih Ting)
E-mail: pyting@cs.ntou.edu.tw TEL: 02 24622192x6615
海洋大學理工學院資訊科學系 Lagoon