C語言檔案處理__C語言

2011年，第一次考對檔案的操作，之後2016年也考了對檔案的操作

題目：讀入一個檔案，對讀入的字串按字元大小排序後，輸出到另外一個檔案

/*讀入一個檔案，對讀入的字串按字元大小排序後，輸出到另外一個檔案*/#include<stdio.h>#include<stdlib.h>int cmp(const void *a, const void *b){return *(char *)a - *(char *)b;}int main(){FILE *in, *out;char inFileName[20] = "in.txt";char outFileName[20] = "out.txt";if ((in = fopen(inFileName, "r")) == NULL){printf("cannot open %s\n", inFileName);exit(0);}if ((out = fopen(outFileName, "w+")) != NULL){//printf("cannot open %s\n", outFileName);//exit(0);}char str[80];int length=0;while (!feof(in)){fscanf(in, "%s", str);fprintf(out, "%s", str);}while (str[length++] != '\0');length = length - 1;qsort(str, length, sizeof(str[0]), cmp);printf("%s", str);fclose(in);fclose(out);

}