我正在运行此代码，但控制台输出错误。应该得到：
Converting 100.00 US dollars into foreign currency leaves $900.00
Charging 100.00 in foreign currency leaves $775.00 Converting 100.00 US dollars into foreign currency leaves
$1900.00
Charging 100.00 in foreign currency leaves $1750.00
但我只得到：
Converting 100.00 US dollars into foreign currency leaves $900.00
这是代码：
#import <Foundation/Foundation.h>
@interface Budget:NSObject {
float exchangeRate;
double budget;
double exchangeTransaction;
}
- (void) createBudget:(double)aBudget withExchangeRate:(float) anExchangeRate;
- (void) spendDollars:(double)dollars;
- (void) chargeForeignCurrency:(double)foreignCurrency;
@end
@implementation Budget
- (void) createBudget:(double)aBudget withExchangeRate:(float) anExchangeRate {
exchangeRate = anExchangeRate;
budget = aBudget;
}
- (void) spendDollars:(double)dollars {
budget -= dollars;
NSLog(@"Converting %.2f US dollars into foreign currency leaves $%.2f", dollars, budget);
}
-(void)chargeForeignCurrency:(double)foreignCurrency {
exchangeTransaction = foreignCurrency * exchangeRate;
budget -= exchangeTransaction;
NSLog(@"Charging %.2f in foreign currency leaves $%.2f", foreignCurrency, budget);
}
@end
int main(int argc, const char * argv[])
{
double numberDollarsInEuroland = 100;
double numberEuros = 100;
double numberDollarsInPoundland = 100;
double numberPounds = 100;
Budget *europeBudget = [Budget new];
[europeBudget createBudget:1000.00 withExchangeRate:1.2500];
[europeBudget spendDollars:numberDollarsInEuroland];
[europeBudget chargeForeignCurrency:numberEuros];
Budget *englandBudget = [Budget new];
[englandBudget createBudget:2000.00 withExchangeRate:1.5000];
[englandBudget spendDollars:numberDollarsInPoundland];
[englandBudget chargeForeignCurrency:numberPounds];
return 0;
}
怎么了？提前致谢。