satie__ars

#include <iostream>
#include <stdio.h>

using namespace std;

int findoperindex(char* a);

int main() {
    setlocale(LC_ALL, "Rus");
    FILE* input, *output;
    char str[100];
    int x, y;
    fopen_s(&input, "input.txt", "r");
    fopen_s(&output, "output.txt", "w");
    while (!feof(input)) {
        fgets(str, 40, input);
        printf("%s", str);
        char number1[3], number2[3];
        int index = findoperindex(str);
        int j = 0, g = 0;
        if (index) {
            for (int i = 0; i < strlen(str); i++) {
                if (i < index) {
                    if ((str[i] > 47) && (str[i] < 58)) {
                        number1[j++] = str[i];
                    }
                }
                if (i > index) {
                    if ((str[i] > 47) && (str[i] < 58)) {
                        number2[g++] = str[i];
                    }
                }
            }
        }
        number1[j] = '\0';
        number2[g] = '\0';
        x = atof(number1);
        y = atof(number2);
        switch (str[index]) {
            case '+':
                fprintf(output, "%1.0i %s %1.0i %s %1.0i \n", x, "+", y, "=", x + y);
                break;
            case '-':
                fprintf(output, "%1.0i %s %1.0i %s %1.0i \n", x, "-", y, "=", x - y);
                break;
            case '*':
                fprintf(output, "%1.0i %s %1.0i %s %1.0i \n", x, "*", y, "=", x * y);
                break;
            case '/':
                fprintf(output, "%1.0i %s %1.0i %s %1.0i \n", x, "/", y, "=", x / y);
                break;
        }
    }
    fclose(input);
    fclose(output);
    return 0;
}

int findoperindex(char* a) {
    for (int i = 0; i < strlen(a); i++) {
        switch (a[i]) {
            case '+':
                return i;

            case '-':
                return i;

            case '*':
                return i;

            case '/':
                return i;
        }
    }
}