#include<stdio.h>
#include<stdlib.h>
#include<math.h>
int main()
{
    int count = 0;
    char ch;
    float x, k = 2.718281, pi = 3.141592, rad = (pi / 180), *num = (float*)malloc(sizeof(float));
    if (num == NULL)
    {
        puts("Error: failed to allocate memory.");
        return;
    }
    printf("Calculate numbers until writing worth and then pressing enter: ");
    while (1)
    {
        if (count > 0)
        {
            scanf(" %f", &num[count]);
            if (ch == '-')
                num[count] = (num[count - 1] - num[count]);
            else if (ch == '+')
                num[count] = (num[count - 1] + num[count]);
            else if (ch == ':')
                num[count] = (num[count - 1] / num[count]);
            else if (ch == '*')
                num[count] = (num[count - 1] * num[count]);
        }
        else
            scanf(" %f", &num[count]);
    finish:
        if (ch == '=')
        {
            scanf(" %c", &ch);
            if (!ch)
            {
                for (int i = count; i >= 0; i--)
                    num[i] = num[i + 1];
                num = (float*)realloc(num, sizeof(float));
                if (num == NULL)
                {
                    puts("Error: failed to allocate memory.");
                    exit(1);
                }
                count = 0;
                printf("Calculate numbers until writing worth and then pressing enter: ");
                float conv;
                conv = atof(ch);
                num[count] = conv;
                goto finish;
            }
            else
                scanf(" %c", &ch);
        }
		scanf(" %c", &ch);
        switch (ch)
        {
        case'-': // subtraction
            count++;
            num = (float*)realloc(num, sizeof(float)*(count + 1));
            if (num == NULL)
            {
                puts("Error: failed to allocate memory.");
                exit(1);
            }
            break;
        case'+': // connecting
            count++;
            num = (float*)realloc(num, sizeof(float)*(count + 1));
            if (num == NULL)
            {
                puts("Error: failed to allocate memory.");
                exit(1);
            }
            break;
        case':': // division
            count++;
            num = (float*)realloc(num, sizeof(float)*(count + 1));
            if (num == NULL)
            {
                puts("Error: failed to allocate memory.");
                exit(1);
            }
            break;
        case'*': // multiplication
            count++;
            num = (float*)realloc(num, sizeof(float)*(count + 1));
            if (num == NULL)
            {
                puts("Error: failed to allocate memory.");
                exit(1);
            }
            break;
        case'=':
            printf("The result is: %f\n", num[count]);
            goto finish;
        case's': // sin
            scanf(" %f", &x);
            num[count] = sin(x*rad);
            goto finish;
        case'c': // cos
            scanf(" %f", &x);
            num[count] = cos(x*rad);
            goto finish;
        case't': // tan
            scanf(" %f", &x);
            if (x == 90 || x == 270)
                puts("Error: no such value.");
            else
                num[count] = (sin(x*rad) / cos(x*rad));
            goto finish;
        case'l': // log
            scanf(" %f", &x);
            num[count] = log10(x);
            goto finish;
        case'e': // exp
            scanf(" %f", &x);
            num[count] = exp(x);
        case'k': // a mathematical constant
            scanf(" %f", &x);
            num[count] = pow(k, x);
            goto finish;
        case'P': // pi
            scanf(" %f", &x);
            num[count] = pow(pi, x);
            goto finish;
        case'n': // tuple
            scanf(" %f", &x);
            float j = 1;
            for (float i = 1; i <= x; i++)
                j *= i;
            num[count] = j;
            j = 1;
            goto finish;
        case'm': // mod
            printf("Enter x: ");
            scanf(" %f", &x);
            int y;
            printf("Enter y: ");
            scanf(" %f", &y);
            num[count] = fmod(x, y);
            goto finish;
        case'/': // root
            num[count] = sqrt(num[count]);
            goto finish;
        case'^': // exponent
            scanf(" %f", &x);
            num[count] = pow(num[count], x);
            goto finish;
        case'R': // reset
            for (int i = count; i >= 0; i--)
                num[i] = num[i + 1];
            num = (float*)realloc(num, sizeof(float));
            if (num == NULL)
            {
                puts("Error: failed to allocate memory.");
                exit(1);
            }
            count = 0;
            printf("Calculate numbers until writing worth and then pressing enter: ");
            break;
        case'Q': // quit
            exit(0);
        default:
            puts("Error: no such char.");
            exit(1);
        }
    }
}