Programação Médio-Avançada: Calculadora em C

#include <stdio.h>
int a,getallen,x,xx,xxx,xxxx,xxxxx,output,doei;
main()


    {
    printf("Calculator");
    printf("\n\nPress 1 for '+'");
    printf("\nPress 2 for '-'");
    printf("\nPress 3 for ':'");
    printf("\nPress 4 for '*'");
    printf("\nChoice: ");
    scanf("%d", &a);


        if ( a == 1 ) {
        printf("\n\n+");
        printf("\nHow many numbers to '+' (2/5)?");
        scanf("%d", &getallen); }


            if ( getallen == 2 ) {
            printf("\nNumber 1: ");
            scanf("%d", &x);
            printf("\nNumber 2: ");
            scanf("%d", &xx);
            output = (int) (x + xx);
            printf("\nOutput = " "%d\n", output);
            scanf("%d", doei); }


                if ( getallen == 3 ) {
                printf("\nNumber 1: ");
                scanf("%d", &x);
                printf("\nNumber 2: ");
                scanf("%d", &xx);
                printf("\nNumber 3: ");
                scanf("%d", &xxx);
                output = (int) (x + xx + xxx);
                printf("\nOutput = " "%d", output);
                scanf("%d", doei); }


                    if ( getallen == 4 ) {
                    printf("\nNumber 1: ");
                    scanf("%d", &x);
                    printf("\nNumber 2: ");
                    scanf("%d", &xx);
                    printf("\nNumber 3: ");
                    scanf("%d", &xxx);
                    printf("\nNumber 4: ");
                    scanf("%d", &xxxx);
                    output = (int) (x + xx + xxx + xxxx);
                    printf("\nOutput = " "%d", output);
                    scanf("%d", doei); }


                        if ( getallen == 5 ) {
                        printf("\nNumber 1: ");
                        scanf("%d", &x);
                        printf("\nNumber 2: ");
                        scanf("%d", &xx);
                        printf("\nNumber 3: ");
                        scanf("%d", &xxx);
                        printf("\nNumber 4: ");
                        scanf("%d", &xxxx);
                        printf("\nNumber 5: ");
                        scanf("%d", &xxxxx);
                        output = (int) (x + xx + xxx + xxxx + xxxxx);
                        printf("\nOutput = " "%d", output);
                        scanf("%d", doei); }


                            if ( a == 2 ) {
                            printf("\n\n-");
                            printf("\nHow many numbers to '-' (2/5)?");
                            scanf("%d", &getallen); }


                                if ( getallen == 2 ) {
                                printf("\nNumber 1: ");
                                scanf("%d", &x);
                                printf("\nNumber 2: ");
                                scanf("%d", &xx);
                                output = (int) (x - xx);
                                printf("\nOutput = " "%d", output);
                                scanf("%d", doei); }


                                    if ( getallen == 3) {
                                    printf("\nNumber 1: ");
                                    scanf("%d", &x);
                                    printf("\nNumber 2: ");
                                    scanf("%d", &xx);
                                    printf("\nNumber 3: ");
                                    scanf("%d", &xxx);
                                    output = (int) (x - xx - xxx);
                                    printf("\nOutput = " "%d", output);
                                    scanf("%d", doei); }


                                        if ( getallen == 4) {
                                        printf("\nNumber 1: ");
                                        scanf("%d", &x);
                                        printf("\nNumber 2: ");
                                        scanf("%d", &xx);
                                        printf("\nNumber 3: ");
                                        scanf("%d", &xxx);
                                        printf("\nNumber 4: ");
                                        scanf("%d", &xxxx);
                                        output = (int) (x - xx - xxx - xxxx);
                                        printf("\nOutput = " "%d", output);
                                        scanf("%d", doei); }


                                            if ( getallen == 5) {
                                            printf("\nNumber 1: ");
                                            scanf("%d", &x);
                                            printf("\nNumber 2: ");
                                            scanf("%d", &xx);
                                            printf("\nNumber 3: ");
                                            scanf("%d", &xxx);
                                            printf("\nNumber 4: ");
                                            scanf("%d", &xxxx);
                                            printf("\nNumber 5: ");
                                            scanf("%d", &xxxxx);
                                            output = (int) (x - xx - xxx - xxxx - xxxxx);
                                            printf("Output = " "%d", output);
                                            scanf("%d", doei); }


                                                if ( a == 3 ) {
                                                printf("\n\n:");
                                                printf("\nHow many numbers to ':' (2/5)?");
                                                scanf("%d", &getallen); }


                                                    if ( getallen == 2) {
                                                    printf("\nNumber 1: ");
                                                    scanf("%d", &x);
                                                    printf("\nNumber 2: ");
                                                    scanf("%d", &xx);
                                                    output = (int) (x / xx);
                                                    printf("\nOutput = " "%d", output);
                                                    scanf("%d", doei); }


                                                        if ( getallen == 3) {
                                                        printf("\nNumber 1: ");
                                                        scanf("%d", &x);
                                                        printf("\nNumber 2: ");
                                                        scanf("%d", &xx);
                                                        printf("\nNumber 3: ");
                                                        scanf("%d", &xxx);
                                                        output = (int) (x / xx / xxx);
                                                        printf("\nOutput = " "%d", output);
                                                        scanf("%d", doei); }


                                                            if ( getallen == 4) {
                                                            printf("\nNumber 1: ");
                                                            scanf("%d", &x);
                                                            printf("\nNumber 2: ");
                                                            scanf("%d", &xx);
                                                            printf("\nNumber 3: ");
                                                            scanf("%d", &xxx);
                                                            printf("\nNumber 4: ");
                                                            scanf("%d", &xxxx);
                                                            output = (int) (x / xx / xxx / xxxx);
                                                            printf("\nOutput = " "%d", output);
                                                            scanf("%d", doei); }


                                                                if ( getallen == 5) {
                                                                printf("\nNumber 1: ");
                                                                scanf("%d", &x);
                                                                printf("\nNumber 2: ");
                                                                scanf("%d", &xx);
                                                                printf("\nNumber 3: ");
                                                                scanf("%d", &xxx);
                                                                printf("\nNumber 4: ");
                                                                scanf("%d", &xxxx);
                                                                printf("\nNumber 5: ");
                                                                scanf("%d", &xxxxx);
                                                                output = (int) (x / xx / xxx / xxxx / xxxxx);
                                                                printf("\nOutput = " "%d", output);
                                                                scanf("%d", doei); }


                                                                    if ( a == 4 ) {
                                                                    printf("\n\n*");
                                                                    printf("\nHow many numbers to '*' (2/5)?");
                                                                    scanf("%d", &getallen); }


                                                                        if ( getallen == 2) {
                                                                        printf("\nNumber 1: ");
                                                                        scanf("%d", &x);
                                                                        printf("\nNumber 2: ");
                                                                        scanf("%d", &xx);
                                                                        output = (int) (x * xx);
                                                                        printf("\nOutput = " "%d", output);
                                                                        scanf("%d", doei); }


                                                                            if ( getallen == 3) {
                                                                            printf("\nNumber 1: ");
                                                                            scanf("%d", &x);
                                                                            printf("\nNumber 2: ");
                                                                            scanf("%d", &xx);
                                                                            printf("\nNumber 3: ");
                                                                            scanf("%d", &xxx);
                                                                            output = (int) (x * xx * xxx);
                                                                            printf("\nOutput = " "%d", output);
                                                                            scanf("%d", doei); }


                                                                                if ( getallen == 4) {
                                                                                printf("\nNumber 1: ");
                                                                                scanf("%d", &x);
                                                                                printf("\nNumber 2: ");
                                                                                scanf("%d", &xx);
                                                                                printf("\nNumber 3: ");
                                                                                scanf("%d", &xxx);
                                                                                printf("\nNumber 4: ");
                                                                                scanf("%d", &xxxx);
                                                                                output = (int) (x * xx * xxx * xxxx);
                                                                                printf("\nOutput = " "%d", output);
                                                                                scanf("%d", doei); }


                                                                                    if ( getallen == 5) {
                                                                                    printf("\nNumber 1: ");
                                                                                    scanf("%d", &x);
                                                                                    printf("\nNumber 2: ");
                                                                                    scanf("%d", &xx);
                                                                                    printf("\nNumber 3: ");
                                                                                    scanf("%d", &xxx);
                                                                                    printf("\nNumber 4: ");
                                                                                    scanf("%d", &xxxx);
                                                                                    printf("\nNumber 5: ");
                                                                                    scanf("%d", &xxxxx);
                                                                                    output = (int) (x * xx * xxx * xxxx * xxxxx);
                                                                                    printf("\nOutput = " "%d", output);
                                                                                    scanf("%d", doei); }
                                                                                    return 0;
                                                                                }