c primer plus 习题答案(6)

p376.7

A方案

#include<stdio.h>
#include<stdlib.h>
#define LEN 40
void rank(FILE *, FILE *);
int main(void)
{
    FILE *fp, *fc;
    int ch, bp;
    char file1[LEN], file2[LEN];

    puts("enter file1 name");
    if((fp=fopen(gets(file1), "r"))==NULL){
        fputs("can't open", stdout);
        exit(1);
    }

    puts("enter file2 name");
    if((fc=fopen(gets(file2), "r"))==NULL){
        fputs("can't open", stdout);
        exit(2);
    }

    rank(fp, fc);
    if((fclose(fp)!=0)||(fclose(fc)!=0))
        puts("error in closing files");

    system("pause");
    return 0;
}

void rank(FILE *fp, FILE *fc)
{
    int ch, bp;
    while(1){
        while(((ch=getc(fp))!='
')&&ch!=EOF)
            putc(ch, stdout);
        if(ch=='
')
            putc(ch, stdout);
        while(((bp=getc(fc))!='
')&&bp!=EOF)
            putc(bp, stdout);
        if(ch=='
')
            putc(bp, stdout);
        if((ch==EOF)&&(bp==EOF))
            break;
    }
}

B方案

#include<stdio.h>
#include<stdlib.h>
#define LEN 40
void rank(FILE *, FILE *);
int main(void)
{
    FILE *fp, *fc;
    int ch, bp;
    char file1[LEN], file2[LEN];

    puts("enter file1 name");
    if((fp=fopen(gets(file1), "r"))==NULL){
        fputs("can't open", stdout);
        exit(1);
    }

    puts("enter file2 name");
    if((fc=fopen(gets(file2), "r"))==NULL){
        fputs("can't open", stdout);
        exit(2);
    }

    rank(fp, fc);
    if((fclose(fp)!=0)||(fclose(fc)!=0))
        puts("error in closing files");

    system("pause");
    return 0;
}

void rank(FILE *fp, FILE *fc)
{
    int ch, bp;
    while(1){
        while(((ch=getc(fp))!='
')&&ch!=EOF)
            putc(ch, stdout);
        while(((bp=getc(fc))!='
')&&bp!=EOF)
            putc(bp, stdout);
        if((bp=='
')||(ch=='
'))
            printf("
");
        if((ch==EOF)&&(bp==EOF))
            break;
    }
}

p376.8

#include<stdio.h>
#include<stdlib.h>
#define LEN 40
int main(int argc, char *argv[])
{
    FILE *fp, *fc, *fd[LEN];
    char name1[LEN], name2[LEN];
    int ch, bp, count[2]={0}, i, num[LEN]={0};
    if(argc==2){
        puts("enter file1 name");
        if((fp=fopen(gets(name1), "r"))==NULL)
            fputs("can't open", stderr);
        puts("enter file1 name");
        if((fc=fopen(gets(name2), "r"))==NULL)
            fputs("can't open", stderr);

        while((ch=getc(fp))!=EOF)
            if(ch==argv[1][0])
                count[0]++;
        while((bp=getc(fc))!=EOF)
            if(bp==argv[1][0])
                count[1]++;
        
        printf("%s has %d %c
", name1, count[0], *argv[1]);
        printf("%s has %d %c
", name2, count[1], *argv[1]);
    }

    for(i=2; i<argc; i++){
        if((fd[i]=fopen(argv[i], "r"))==NULL){
            fputs("can't open
", stderr);
            continue;
        }
        while((ch=getc(fd[i]))!=EOF)
            if(ch==*argv[1])
                num[i]++;
        printf("%s has %d %c
", argv[i], num[i], *argv[1]);
    }

    system("pause");
    return 0;
}

p376.10

#include<stdio.h>
#include<stdlib.h>
#define LEN 40
int main(void)
{
    FILE *fp;
    char name[LEN];
    long offset;
    int ch;

    puts("enter the file name");
    if((fp=fopen(gets(name), "r"))==NULL){
        fprintf(stderr, "can't open
");
        exit(1);
    }
    puts("enter an offset of file(q to quit)");
    while(scanf("%ld", &offset)==1){
        fseek(fp, offset, SEEK_SET);
        while(((ch=getc(fp))!='
')&&ch!=EOF&&ch!='
')
            fprintf(stdout, "%c", ch);
        if(ch==EOF)
            exit;
        printf("
");
        puts("enter an offset of file(q to quit)");
    }

    fclose(fp);
    system("pause");
    return 0;
}