在檔案裡搜尋字串並取代

在檔案裡搜尋字串並取代 ( 只能搜尋取代一次，無法整篇文章取代 )

int Replaceword (unsigned int size, const char *skeyword, 
                 const char *reword, const char *cfp, const char *cnewfp)
{ 
    char ckw[size];
    unsigned int uikwlen=strlen(skeyword)+1;
    int i=0; // 偏移量 
    FILE *fp=fopen(cfp,"r");
    FILE *newfp=fopen(cnewfp,"w+");
    char check=0;
    
    //找尋keyword的位置 
    for(i=1;fgets(ckw,uikwlen,fp)!=NULL;i++)
    {   //printf("ckw=%s\n",ckw);
        if(strcmp(ckw,skeyword) == 0)
        {
            printf("fine_keyword=%s\n",ckw);
            check=1; // Found
            break;
        }
        rewind(fp);
        if(ckw[0]=='\n') //為了在字串結尾只有一個\n 
            i++;
        fseek(fp,i,SEEK_SET);
        
        fprintf(newfp,"%c",ckw[0]);
    }
    if (!check)
    return 0;
    
    //取代字串 
    fclose(newfp); 
    newfp=fopen(cnewfp,"a+");
    fprintf(newfp,"%s",reword);
    
    //寫入剩下的字串 
    fclose(newfp);
    newfp=fopen(cnewfp,"a+");
    i=i+uikwlen-2; //為何減2，減1 是為了\n，另一個減 1 是...？ 
    fseek(fp,i,SEEK_SET); 
    for(i=i+1;fgets(ckw,uikwlen,fp)!=NULL;i++)
    { 
        //printf("ckw=%s\n",ckw);
        rewind(fp);
        if(ckw[0]=='\n') //為了在字串結尾只有一個\n 
        i++;
        fseek(fp,i,SEEK_SET);
        
        fprintf(newfp,"%c",ckw[0]);
    }


    fclose(newfp);
    fclose(fp);

    return check;

}

int main ()
{
    int a=0;
    const char *fp="C:\\file.txt";
    const char *newfp="C:\\newfile.txt";
    int i; 
    
    a=Replaceword (20,"Ver","VID=VEN_909",fp,newfp);
    
    printf("a=%d\n",a);
    system("pause");
    return 0;
}