#include <stdio.h>
#include <string>
int main(){
float a,b,z,u,r,k;
char f,q,m;
system("color B");
repeat:
printf("Unesite broj a: ");
scanf("%f",&a);
repeatm:
printf("Unesite broj b: ");
scanf("%f",&b);
printf("Unesite funkciju (+,-,*,/): ");
finput:
scanf("%s",&f);
if(f=='+'){
goto zbroj;
}else{
if(f=='-'){
goto razlika;
}else{
if(f=='*'){
goto umnozak;
}else{
if(f=='/'){
goto kolicnik;
}else{
goto _newf;
}
}
}
}
//input of numbers and a check if the value of 'f' is one of the characters +,-,* or /
zbroj:
z=a+b;
printf("-------------------------------------\n");
printf("Zbroj ta dva broja je: ");
printf("%f \n",z);
goto _new;
razlika:
r=a-b;
printf("-------------------------------------\n");
printf("Razlika ta dva broja je: ");
printf("%f \n",r);
goto _new;
umnozak:
u=a*b;
printf("-------------------------------------\n");
printf("Umnozak ta dva broja je: ");
printf("%f \n",u);
goto _new;
kolicnik:
if(b==0){
system("cls");
printf("Ne mozete dijeliti s nulom \n");
goto repeatB;
}else{
k=a/b;
printf("-------------------------------------\n");
printf("Kolicnik ta dva broja je: ");
printf("%f \n",k);
goto _new;
}
//prints results
_newf:
printf("Nevazeca funkcija, upisite ponovo: ");
goto finput;
//loop if 'f' isnt one of +,-,*,/
_new:
printf("-------------------------------------\n");
printf("Novi racun?(y/n) ");
scanf("%s",&q);
system("cls");
goto repeat1;
//asks if i want to exit or go back to start
repeat1:
if(q=='y'){
system("cls");
goto memory;
}else{
if(q=='n'){
goto exit;
}else{
printf("Novi racun? \n");
printf("Molimo upisite y ili n: ");
scanf("%s", &q);
goto repeat1;
}
}
//loops back to start
memory:
printf("Zelite li iskoristits peredhodni rezultat kao broj a?(y/n): ");
scanf("%s", &m);
//asks if i want the previous result as the number 'a'
repeat2:
if(m=='y'){
system("cls");
goto printfa;
}else{
if(m=='n'){
system("cls");
goto repeat;
}else{
printf("Zelite li iskoristits peredhodni rezultat kao broj a? \n");
printf("Molimo upisite y ili n: ");
scanf("%s", &m);
goto repeat2;
}
}
//checks if variable 'm' is either y or n
printfa:
if(f=='+'){
a=z;
}else{
if(f=='-'){
a=r;
}else{
if(f=='*'){
a=u;
}else{
if(f=='/'){
a=k;
}
}
}
}
//this should(?) overwrite the variable 'a'
//why isnt 'a' overwritten with the value of 'z', 'r', 'u' or 'k' here?
printf("Broj a je: %f \n", a);
//here the value of 'a' stays the same as it was before
goto repeatm;
repeatB:
printf("Unesite broj b: ");
scanf("%f",&b);
goto kolicnik;
exit:
system("cls");
system("pause");
return(0);
}
is there any way to overwrite the variable 'a' (without manual input) with one of the values of 'z', 'r', 'u' or 'k'. the result of this code is just a + (or -,*,/) new b (which i manualy input again, but the variable a stays the same as the first input). pleas dont mind the foreign language it just says "input a", "input b", "the result is..", also sorry if the code is messy..
I can only answer the question indirectly, because I didn't start looking into the actual problem until after I had cleaned the code up a little bit - but now I don't get the error. So, the answer is: clean up the code and it'll probably work as expected.
I've kept saving the result in different variables although nothing in the program needs to have more than one result variable as it is right now. The main flow of the program should be like your original but it's just a tad easier to read now:
#include <iostream>
#include <string>
// helper functions
bool yes_or_no(const std::string& question) {
char answer;
do {
std::cout << question << " (y/n) ";
std::cin >> answer;
} while(answer != 'y' && answer != 'n');
return answer == 'y';
}
void line() { std::cout << "-------------------------------------\n"; }
void display_result(const std::string& heading, float value) {
std::cout << heading << " ta dva broja je: " << value << "\n";
}
int main() {
float op_a, op_b, add_res = 0, mul_res = 0, sub_res = 0, div_res = 0;
char oper;
bool save_op_a = false;
system("color B");
while(true) {
system("cls");
if(save_op_a == false) {
std::cout << "Unesite broj a: ";
std::cin >> op_a;
} else
save_op_a = false;
std::cout << "Unesite broj b: ";
std::cin >> op_b;
while(true) {
std::cout << "Unesite funkciju (+,-,*,/): ";
std::cin >> oper;
line();
if(oper == '+') {
add_res = op_a + op_b;
display_result("Zbroj", add_res);
break;
} else if(oper == '-') {
sub_res = op_a - op_b;
display_result("Razlika", sub_res);
break;
} else if(oper == '*') {
mul_res = op_a * op_b;
display_result("Umnozak", mul_res);
break;
} else if(oper == '/') {
if(op_b == 0.) {
std::cout << "Ne mozete dijeliti s nulom\n";
continue;
}
div_res = op_a / op_b;
display_result("Kolicnik", div_res);
break;
}
}
line();
if(yes_or_no("Novi racun?")) {
system("cls");
// asks if i want the previous result as the number 'op_a'
if(yes_or_no("Zelite li iskoristits peredhodni rezultat kao broj a?")) {
// this should(?) overwrite the variable 'op_a'
// why isnt 'op_a' overwritten with the value here?
system("cls");
if(oper == '+') {
op_a = add_res;
} else if(oper == '-') {
op_a = sub_res;
} else if(oper == '*') {
op_a = mul_res;
} else if(oper == '/') {
op_a = div_res;
}
// here the value of 'op_a' stays the same as it was before
std::cout << "Broj a je: " << op_a << "\n";
save_op_a = true;
}
} else
break; // exit
}
system("cls");
system("pause");
return (0);
}