为什么ftell会跳过文件中的某些位置?[副本]

line 1
l

#include<stdio.h>
int main(){
    FILE *f = fopen("myfile.txt","r");
    if(f==NULL){
        FILE *fp=fopen("myfile.txt","w");
        fclose(fp);
        f = fopen("myfile.txt","r");
    }
    while(!feof(f)){
        printf("\ncharacter number %d    ",ftell(f));
        putchar(fgetc(f));      
    }
    fclose(f);
    return 0;
}

输出为:

character number 0    l
character number 1    i
character number 2    n
character number 3    e
character number 4
character number 5    1
character number 6

character number 8    l
character number 9      

每当遇到一个值时,ftell就会跳过一个值,例如它跳过了值7。为什么会这样?请详细解释我,我想知道。