第五集cfan编程大赛2.c题及源代码

题目如下：

现有一个班的某次考试成绩,文件名为 exam.txt,请作出相关的统计,要求如下:
   读取 exam.txt,此文本文件第一行为一个整数 N,表示学生人数(N<=50000)。
1.
   以下为 N 行,每一行的数据依次包括:考生姓名、考试成绩(姓名为长度不超过
   4 个字符的字符串,成绩为一个不大于 109 的正整数)  ,用一个空格分开。
   统计此次考试的数据,包括:平均分、最高分、方差,对此次考试的考生成绩进
2.
   行从高分到低分的排序(分数相同时排序顺序任意)      。
   在当前目录下创建一个文件名为 output.txt 的文本文件。在文件开始的前四
3.
   行依次输出平均分、最高分和方差,均保留小数点后四位。接下来的 N
   行每行输出一个考生的姓名和成绩,    用空格分开, 按照从高分到低分的顺序输出。
 
4. 程序运行时可以不显示界面,也可设计一个窗体,用于显示处理进度。

 

源代码如下：

分三个部分，主模块main.c，自定义头文件_my.h，自定义头文件的实现文件_my.c

 

_my.h源码

/*************************************************************FILE :_my.h ***************************************************************PURPOSE :head file _my.h used by main.c ***************************************************************ENVIRONMENT:Fedora_i386 + Code::Blocks + GUN C Compiler ***************************************************************STANDARD :ISO/IEC 9899:1999 & ISO/IEC 9899:1990 ** compatable with VC++ & TC & GCC TAB=4 ***************************************************************AUTHOER :davelv & 2009-06-20 & [e-mail] *************************************************************//***************************************** preprocess instuctions *****************************************/#ifndef __MY_H/*include it */#define __MY_H 1/*fobid IO warnings in VC*/#ifdef WIN32#define _CRT_SECURE_NO_WARNINGS#endif/*define Macro constant*/#define OK_D 0#define READ_ERR_D 1#define WRITE_ERR_D 2#define MALLOC_ERR_D 3#define READ_ERR_STR "READ_ERROR"#define WRITE_ERR_STR "WRITE_ERROR"#define MALLOC_ERR_STR "MALLOC_ERROR"#define UNKOWN_ERR_STR "UNKOWN_ERROR"/*define Macro function*/#define CHK_RET(RET,ERR) if((RET)!=OK_D)/ {/ perror(ERR);/ exit(RET);/ }/***************************************** declare type & functions *****************************************//*define student type*/typedef struct{ char name[9]; long score;}student;/*compare two values used by qsort()*/extern int compare(void const *a,void const *b);#endif  _my.c源代码

/*************************************************************FILE :_my.c ***************************************************************PURPOSE :implementation of head file _my.h ***************************************************************ENVIRONMENT:Fedora_i386 + Code::Blocks + GUN C Compiler ***************************************************************STANDARD :ISO/IEC 9899:1999 & ISO/IEC 9899:1990 ** compatable with VC++ & TC & GCC TAB=4 ***************************************************************AUTHOER :davelv & 2009-06-20 & [e-mail] *************************************************************/#include "_my.h"/*************************************************************FUNCTION :compare() ***************************************************************PURPOSE :compare two variables used by qsort() ***************************************************************ARGUMENTS :void *a :the one variable pointer to compare** void *b :anthoer variable pointer to compare***************************************************************RETURN :int 0 :equale ** <0 :fist varible is lower than second ** >0 :fist varible is greater than second***************************************************************COMMENTS :you should be sure that the pointer isn't NULL *************************************************************/extern int compare(void const *a,void const *b){ return( ((student*)b)->score-((student*)a)->score );} main.c源代码

/*************************************************************FILE :main.c ***************************************************************PURPOSE :Read process and write student info form ** exam.txt to output.txt ***************************************************************ENVIRONMENT:Fedora_i386 + Code::Blocks + GUN C Compiler ***************************************************************STANDARD :ISO/IEC 9899:1999 & ISO/IEC 9899:1990 ** compatable with VC++ & TC & GCC TAB=4 ***************************************************************AUTHOER :davelv & 2009-06-20 & [e-mail] *************************************************************//***************************************** preprocess instuctions *****************************************/#include "_my.h"#include <stdio.h>#include <stdlib.h>/***************************************** declare and define globle variables *****************************************//*totle number of student ,the max score in all student scores*/static long totle,max_score;/*average of score,sum of score variance of score*/static double average_score,sum_score,variance;/***************************************** declare functions *****************************************//*process student info*/static int process(student *stu);/*finalize used files and malloced memory*/static int finalize(FILE *in, FILE *out,student *stu);/*write all info into out file*/static int write_file(FILE *const out, student *const stu);/*read all info from in file*/static int read_file(FILE * const in,student ** const stu_p);/*initialize in and out files*/static int init_file(FILE **const read_file,FILE **const write_file,char const *const read_file_name,char const *const write_file_name);/*************************************************************FUNCTION :main() ***************************************************************PURPOSE :main control function of the program ***************************************************************ARGUMENTS :void ***************************************************************RETURN :int OK_D :success ** READ_ERR_D :error when open read file ** WRITE_ERR_D :error when open write file ** MALLOC_EER_D:error when malloc memory ***************************************************************COMMENTS :call other other functions and check their ** return values to control the hole program *************************************************************/int main(void){ /*in & out file pointers */ static FILE *in,*out; /*pionter to student info*/ static student *stu; /*storage return value from other functions*/ static int rets; /*initial files*/ rets=init_file(&in,&out,"exam.txt","output.txt"); CHK_RET(rets,rets==READ_ERR_D?READ_ERR_STR:WRITE_ERR_STR);/*check the returns by use macro in _my.h*/ puts("Initial files done!"); /*read data from file;*/ rets=read_file(in,&stu); CHK_RET(rets,rets==MALLOC_ERR_D?MALLOC_ERR_STR:UNKOWN_ERR_STR); puts("Read data done!"); /*process data;*/ rets=process(stu); CHK_RET(rets,UNKOWN_ERR_STR); puts("Process data done!"); /*write data to file*/ rets=write_file(out,stu); CHK_RET(rets,UNKOWN_ERR_STR); puts("Write data done!"); /*finalize*/ rets=finalize(in,out,stu); CHK_RET(rets,UNKOWN_ERR_STR); puts("Program done!"); return OK_D;}/*************************************************************FUNCTION :init_file() ***************************************************************PURPOSE :initialize in and out files used by program ***************************************************************ARGUMENTS :FILE **read_file :piont read file pointer ** FILE **write_file :piont write file pointer ** char *read_file_name :read file name ** char *write_file_name :write file name ***************************************************************RETURN :int OK_D :success ** READ_ERR_D :error when open read file ** WRITE_ERR_D :error when open write file***************************************************************COMMENTS :change *read_file *write_file to object files. ** static file scope,you can use it only in this ** source file!!! *************************************************************/static int init_file(FILE **const read_file,FILE **const write_file,char const *const read_file_name,char const *const write_file_name){ /*initial&check read file*/ if((*read_file=fopen(read_file_name,"r"))==NULL) return READ_ERR_D; /*initial&check write file*/ if((*write_file=fopen(write_file_name,"w"))==NULL) return WRITE_ERR_D; return OK_D;}/*************************************************************FUNCTION :read_file() ***************************************************************PURPOSE :read info from read file ***************************************************************ARGUMENTS :FILE *in :read file pointer ** student**stu_p :piont to student info pointer***************************************************************RETURN :int OK_D :success ** MALLOC_EER_D:error when malloc memory ***************************************************************COMMENTS :change *stu_p to the begining of student info ** change globle variable totle ** static file scope,you can use it only in this ** source file!!! *************************************************************/static int read_file(FILE * const in,student ** const stu_p){ /*current student info pointer,end pointer */ static student *stu_now,*stu_end; extern long totle; /*read number*/ fscanf(in,"%ld",&totle); /*malloc from memory*/ if((*stu_p=(student *)malloc(totle*sizeof(student)))==NULL) return MALLOC_ERR_D; /*read students info*/ for(stu_now=*stu_p,stu_end=stu_now+totle;stu_now<stu_end;stu_now++) { fscanf(in,"%s %ld",stu_now->name,&stu_now->score); } return OK_D;}/*************************************************************FUNCTION :process() ***************************************************************PURPOSE :calc score and sort the student info ***************************************************************ARGUMENTS :student *stu :student info pointer ***************************************************************RETURN :int OK_D :success ***************************************************************COMMENTS :change squance of student info by score from ** high to low. ** change globle variables:sum_score,average_score** ,variance,max_score. ** static file scope,you can use it only in this ** source file!!! *************************************************************/static int process(student *stu){ static long i; extern double sum_score,average_score,variance; extern long max_score,totle; /*calc sum_score,find max_score*/ for(i=0,sum_score=0,max_score=stu[0].score;i<totle;i++) { sum_score+=stu[i].score; if(stu[i].score>max_score) max_score=stu[i].score; } /*calc average_score*/ average_score=sum_score/totle; /*calc variance*/ for(i=0,variance=0;i<totle;i++) { variance+=(stu[i].score-average_score)*(stu[i].score-average_score); } variance/=totle; /*sort student info by score from high to low*/ qsort(stu,totle,sizeof(student),compare); return OK_D;}/*************************************************************FUNCTION :write_file() ***************************************************************PURPOSE :write all info into write file ***************************************************************ARGUMENTS :FILE *out :out file pointer ** student *stu :student info pointer ***************************************************************RETURN :int OK_D :success ***************************************************************COMMENTS :write average_score,max_score,varance into ** write file by retention decimal point latter 4 ** write all student info into write file as read ** static file scope,you can use it only in this ** source file!!! *************************************************************/static int write_file(FILE *const out, student *const stu){ static long i; extern double average_score,variance; extern long max_score,totle; /*write head info*/ fprintf(out,"%4lf/n%4lf/n%4lf/n",average_score,(double)max_score,variance); /*write every student info*/ for(i=0;i<totle;i++) fprintf(out,"%s %ld/n",stu[i].name,stu[i].score); return OK_D;}/*************************************************************FUNCTION :finalize() ***************************************************************PURPOSE :finalize the used resource ***************************************************************ARGUMENTS :FILE *in :in file pointer ** FILE *out :out file pointer ** student *stu :student info pointer ***************************************************************RETURN :int OK_D :success ***************************************************************COMMENTS :close in&out files,free the malloced momery ** static file scope,you can use it only in this ** source file!!! *************************************************************/static int finalize(FILE *in, FILE *out,student *stu){ free(stu); fclose(in); fclose(out); return OK_D;}