Lab_for_sasha_13

#include <stdio.h>

int main() {
    FILE *afile = NULL;
    FILE *bfile = NULL;
    FILE *cfile = NULL;
    cfile = fopen("C", "w");
    if (cfile == NULL) {
        puts("Error create file C");
        return 0;
    }
    afile = fopen("A", "r");
    if (afile ==NULL){
        puts("Error open file A");
        return 0;
    }
    char symbol;
    while(fread(&symbol,sizeof(char), 1, afile)== sizeof(char)){
        if (symbol == '>' || symbol == '=' || symbol == '<'){
            fwrite(&symbol,sizeof(char), 1, cfile);
        }
    }
    fclose(cfile);
    fclose(afile);
    bfile = fopen("B", "r");
    if (bfile == NULL) {
        puts("Error create file C");
        return 0;
    }
    afile = fopen("A", "a");
    if (afile ==NULL){
        puts("Error open file A");
        return 0;
    }
    while(fread(&symbol,sizeof(char), 1, bfile)== sizeof(char)){
        if ((symbol >='a' && symbol <= 'z') || (symbol >= 'A' && symbol <= 'Z')){
            fwrite(&symbol,sizeof(char), 1, afile);
        }
    }
    fclose(bfile);
    fclose(afile);
    fclose(cfile);
    return 0;
}