文章目录
- 一、实现思路
- 二、实现方法
- 三、判错处理
一、实现思路
先搭建好MVC框架，接着在各个模块中实现各自的任务。首先要创建好UI界面，接着根据UI界面的元素来与数据进行互动，其中创建UI界面需要用到Masonry布局。
二、实现方法
在calculationView文件中只涉及到UI界面。
首先创建两个UITextField对象，一个用来显示输入到表达式，一个用来输出运算结果，接着创建一个数组用来存放button的名称，接着循环创建button对象即可。
创建button时需要设置button的tag属性，因为后面需要通过button的tag属性来进行逻辑判断。
self.textField01 = [[UITextField alloc] init];
self.textField01.backgroundColor = [UIColor blackColor];
self.textField02 = [[UITextField alloc] init];
self.textField02.backgroundColor = [UIColor blackColor];
self.buttonArray = [NSMutableArray arrayWithObjects:@"AC", @"(", @")", @"/", @"1", @"2", @"3", @"+", @"4", @"5", @"6", @"-", @"7", @"8", @"9", @"*", @"0", @".", @"=", nil];
for (int i = 0; i < 4; i++) {
for (int j = 0; j < 4; j++) {
self.calculatorButton = [UIButton buttonWithType:UIButtonTypeCustom];
NSString* buttonString = self.buttonArray[i * 4 + j];
[self.calculatorButton setTitle:buttonString forState:UIControlStateNormal];
self.calculatorButton.titleLabel.font = [UIFont systemFontOfSize:43];
self.calculatorButton.titleLabel.textColor = [UIColor whiteColor];
self.calculatorButton.backgroundColor = [UIColor grayColor];
[self.calculatorButton addTarget:self action:@selector(pressButton:) forControlEvents:UIControlEventTouchUpInside];
self.calculatorButton.layer.borderWidth = 2.0;
self.calculatorButton.layer.cornerRadius = ButtonSize / 2;
self.calculatorButton.layer.masksToBounds = YES;
self.calculatorButton.tag = 100 + j + i*4;
if (i == 0 && j < 3) {
self.calculatorButton.backgroundColor = [UIColor colorWithWhite:0.6 alpha:0.9];
self.calculatorButton.titleLabel.textColor = [UIColor blackColor];
}
if (j == 3) {
self.calculatorButton.backgroundColor = [UIColor orangeColor];
}
[self addSubview:self.calculatorButton];
[self.calculatorButton mas_makeConstraints:^(MASConstraintMaker *make) {
make.top.equalTo(self).offset(90 + HEIGHT / 6 + HEIGHT / 8 + (ButtonSize + SideSize) * i);
make.left.equalTo(self).offset(SideSize + (ButtonSize + SideSize) * j);
make.width.equalTo(@ButtonSize);
make.height.equalTo(@ButtonSize);
}];
}
}
还需要在当前文件触发button的事件函数，因为要通过button的事件函数将当前button传值到CalculationViewController文件中。
我使用的协议传值进行
定义协议及协议方法
@protocol ButttonDelegate <NSObject>
- (void)returnButton:(UIButton*)button;
@end
定义代理对象
@property (nonatomic, weak)id<ButttonDelegate>delegate;
button事件函数触发代理方法
- (void)pressButton:(UIButton*)button {
[self.delegate returnButton:button];
}
在CalculationViewController中定义协议方法
- (void)returnButton:(UIButton*)button;
在CalculationViewController中设置代理对象
self.calculationView.delegate = self;
在CalculationViewController中实现协议方法
- (void)returnButton:(UIButton*)button {
- NSString* buttonStr = button.titleLabel.text;
NSInteger buttonTag = button.tag;
if (buttonTag == 100) {
self.calculationView.textField01.text = @"";
self.calculationView.textField02.text = @"";
self.yunsuanStr = [[NSMutableString alloc] init];
self.jieguoStr = [[NSString alloc] init];
} else if (buttonTag == 118) {
//四则运算
}
//
}
对于四则运算，我使用中缀表达式转后缀表达式，再利用后缀表达式进行计算。中缀转后缀定义一个符号栈，一个结果栈。
char resultStack[100];
int resultTop = -1;
char operationStack[100];
int operationTop = -1;
NSString* ocStr = self.yunsuanStr;
const char* strs = [ocStr UTF8String];
char str[1000] ;
strcpy(str, strs) ;
int length = (int)strlen(str);
后缀进行四则运算时定义一个新栈。
double Stack[100];
int StackTop = -1;
char* token = strtok(resultStack, " ");
while (token != NULL) {
if (strcmp(token, "+") == 0) {
double a = Stack[StackTop--];
double b = Stack[StackTop--];
double c = b + a;
Stack[++StackTop] = c;
}
else if (strcmp(token, "-") == 0) {
double a = Stack[StackTop--];
double b = Stack[StackTop--];
double c = b - a;
Stack[++StackTop] = c;
}
else if (strcmp(token, "*") == 0) {
double a = Stack[StackTop--];
double b = Stack[StackTop--];
double c = b * a;
Stack[++StackTop] = c;
}
else if (strcmp(token, "/") == 0) {
double a = Stack[StackTop--];
double b = Stack[StackTop--];
double c = b / a;
Stack[++StackTop] = c;
}
else if (strcmp(token, "!") == 0) {
double c = Stack[StackTop--];
c = -c;
Stack[++StackTop] = c;
}
else {
double num = atof(token);
Stack[++StackTop] = num;
}
token = strtok(NULL, " ");
}
double result = Stack[StackTop--];
这里使用了atof()函数可以将字符串中的数字识别为double类型的浮点数。使用strtok()函数将结果栈的元素通过空格分割方便进行识别和运算。
对于负数的运算，我是将与“（”相邻的“-”转换为“！”，并用“！”进行负数转变，其中需要将“！“的优先级设置为最高
int Compare(char str) {
if (str == '(' || str == ')') {
return 0;
}
else if (str == '+' || str == '-') {
return 1;
}
else if (str == '*' || str == '/') {
return 2;
} else if (str == '!') {
return 3;
} else {
return -1;
}
}
接着在输入字符串时进行识别
for (int i = 0; i < length; ++i) {
if (str[i] == '(' && str[i + 1] == '-') {
str[i + 1] = '!';
}
}
三、判错处理
对于括号匹配问题，我使用栈来处理，当读到“（”则入栈，读到“）”则栈顶元素出栈，最后判断栈是否为空即可。
- (int)kuoHaoMatch:(NSMutableString*)mutableString {
const char* cstr = [mutableString UTF8String];
int length = (int)strlen(cstr);
char stack[100];
int stackTop = -1;
for (int i = 0; i < length; i++) {
if (cstr[i] == '(') {
stack[++stackTop] = cstr[i];
}
if (cstr[i] == ')') {
stack[stackTop--];
}
}
if (stackTop == -1) {
return 1;
}
return 0;
}
对于符号匹配问题，两个运算符不能相邻，第一个位置不能为运算符（-除外），最后一个位置不能为运算符
- (int)fuHaoMatch:(NSMutableString*)mutableString {
const char* cstr = [mutableString UTF8String];
int length = (int)strlen(cstr);
if (cstr[0] == '*' || cstr[0] == '/' || cstr[0] == '+') {
return 0;
}
for (int i = 0; i < length; i++) {
if ((cstr[i] == '*' && cstr[i+1] == '/') || (cstr[i] == '/' && cstr[i+1] == '*')) {
return 0;
}
if ((cstr[i] == '*' && cstr[i+1] == '-') || (cstr[i] == '*' && cstr[i+1] == '+')) {
return 0;
}
if ((cstr[i] == '/' && cstr[i+1] == '-') || (cstr[i] == '/' && cstr[i+1] == '+')) {
return 0;
}
if ((cstr[i] == '+' && cstr[i+1] == '/') || (cstr[i] == '+' && cstr[i+1] == '*')) {
return 0;
}
if ((cstr[i] == '-' && cstr[i+1] == '/') || (cstr[i] == '-' && cstr[i+1] == '*')) {
return 0;
}
if ((cstr[i] == '-' && cstr[i+1] == '-') || (cstr[i] == '-' && cstr[i+1] == '+')) {
return 0;
}
if ((cstr[i] == '+' && cstr[i+1] == '+') || (cstr[i] == '+' && cstr[i+1] == '-')) {
return 0;
}
}
if (cstr[length - 1] == '+' || cstr[length - 1] == '-' ||cstr[length - 1] == '*' || cstr[length - 1] == '/') {
return 0;
}
return 1;
}
对于数字和括号的相邻问题，数字后不能直接跟左括号，右括号不能直接跟数字
- (int)numberAndkuoHao:(NSMutableString*)mutableString {
const char* cstr = [mutableString UTF8String];
int length = (int)strlen(cstr);
int flag = 0;
for (int i = 0; i < length; i++) {
if ((cstr[i]>= '0' && cstr[i] <= '9') &&cstr[i+1] == '(') {
flag++;
}
if (cstr[i] == ')' && (cstr[i + 1]>= '0' && cstr[i + 1] <= '9')) {
flag++;
}
}
if (flag == 0) {
return 1;
}
return 0;
}
对于只有括号没有数字的问题，直接遍历整个字符串如果有数字则标志变量加一，最后判断标志变量
- (int)numberJudge:(NSMutableString*)mutableString {
const char* cstr = [mutableString UTF8String];
int length = (int)strlen(cstr);
int flag = 0;
for (int i = 0; i < length; i++) {
if (cstr[i]>= '0' && cstr[i] <= '9') {
flag++;
}
}
if (flag != 0) {
return 1;
}
return 0;;
}
对于除零问题
if ([self.jieguoStr isEqualToString:@"nan"]) {
self.jieguoStr = @"错误";
}
if ([self.jieguoStr isEqualToString:@"inf"]) {
self.jieguoStr = @"错误";
}
对于小数点异常处理
int pointFlag = 0;
for (int i = 0; i < resultTop; i++) {
if (resultStack[i] == '.') {
for (int j = i + 1; resultStack[j] != ' '; j++) {
if (resultStack[j] == '.') {
pointFlag++;
}
}
}
}
if (pointFlag != 0) {
self.jieguoStr = @"错误";
pointFlag = 0;
}
对于如何删除多余的零
NSDecimalNumber *number = [NSDecimalNumber decimalNumberWithString: self.jieguoStr];
NSDecimalNumberHandler *roundHandler = [NSDecimalNumberHandler decimalNumberHandlerWithRoundingMode:NSRoundUp scale:8 raiseOnExactness:NO raiseOnOverflow:NO raiseOnUnderflow:NO raiseOnDivideByZero:NO];
NSDecimalNumber *roundedNumber = [number decimalNumberByRoundingAccordingToBehavior:roundHandler];
self.jieguoStr = [roundedNumber stringValue];
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