090928日c语言学习日记（文件I/O)

#include<stdio.h>
#include<stdlib.h>
#define MAX 41
static int i=0;
int main(void)
{
FILE *fp;
char words[MAX];
if((fp=fopen("words","a+"))==NULL)
{
fprintf(stdout,"Can't open \" word\" file\n");
exit(1);
}
puts("Enter words to add to the file,press the enter.");
puts("Key at the begining of a line to terminate.");
while(gets(words)!=NULL&&words[0]!='\0')
{
fprintf(fp,"%s",words);
i++;
}
rewind(fp);
while(fscanf(fp,"%s",words)==1)
{
puts(words);
}
if(fclose(fp)!=0)
{
fprintf(stderr,"Error closing file.\n");
}
return 0;
}

#include<stdio.h>
#include<stdlib.h>
#define MAX 2000
int main(void)
{
FILE *fp;
char words[MAX];
int wordct=0;
if((fp=fopen("words","a+"))==NULL)
{
fprintf(stderr,"Can't open \" word\" file\n");
exit(1);
}
rewind(fp);
while (fgets(words, MAX - 1, fp) != NULL)
wordct++;
rewind(fp);
puts("Enter words to add to the file,press the enter.");
puts("Key at the begining of a line to terminate.");
while(gets(words)!=NULL&&words[0]!='\0')
{
fprintf(fp,"%d:%s",++wordct,words);
}
puts("File contents:");
rewind(fp);
while(fgets(words,MAX-1,fp)!=NULL)
{
fputs(words,stdout);
}
if(fclose(fp)!=0)
{
fprintf(stderr,"Error closing file.\n");
}
return 0;
}
/*文件名由用户输入，建立一个循环，让用户输入文件位置，
则打印位置到下一个换行符之间的字符，当输入非数字字符时退出*/
#include<stdio.h>
#include<stdlib.h>
#include<ctype.h>
#define MAX 41
int main(void)
{
FILE *fp;
char ch;
char file[MAX];
long address;
puts("请输入文件名");
gets(file);
if((fp=fopen(file,"rb"))==NULL)
{
fprintf(stderr,"Can't open the %s\n",file);
exit(1);
}


printf("请输入一个文件位置\n");
while(1)
{
scanf("%ld",&address);
if(isdigit(address))
{
break;
}
fseek(fp,address,SEEK_SET);

while((ch=getc(fp))!='\n' && (ch=getc(fp)