ЦЕЗАР

int main(){
int k;
scanf("%d",&k);
writeToFile();
FILE *p1=fopen("text5.txt","r");
FILE *p2=fopen("text6.txt","w");
char c;
while((c=fgetc(p1))!=EOF){
    int ascii;
    if(isalpha(c)){
    ascii = c + k;
    if(islower(c)){
    if(ascii>122){
        c = ascii-26; // zoshto ima 26 bukvi vo azbukata
    }else{
        c = c+k;
    }
    }else{
    if(ascii>90){
        c = ascii-26;
    }else{
        c = c+k;
    }
    }
    }
    fputc(c,p2);
    printf("%c",c);
}
fclose(p1);
fclose(p2);
return 0;
}