C++实现正整数的四则运算表达式

 #include  #include  using namespace std; int main() { int i, j, k, len = 0, lenf = 0, lenl = 0, op = 0, z = 0, y = 0, sum = 0; char algorithm[100], f[50] = {0}, l[50] = {0}; cout << "input an expression with one of the four fundamental operations: "; gets(algorithm); //计算初始字符串长度 for (i = 0; algorithm[i] != '\0'; ++i) { len += 1; } //提取运算符号前的字符串 for (j = 0; ('0' <= algorithm[j] && algorithm[j] <= '9') || algorithm[j] == ' '; ++j) { f[j] = algorithm[j]; } //判断运算符号 if (algorithm[j] == '+')op = 1; if (algorithm[j] == '-')op = 2; if (algorithm[j] == '*')op = 3; if (algorithm[j] == '/')op = 4; while (algorithm[j + 1] == ' ')++j; //提取运算符号后的字符串 for (k = j + 1; algorithm[k] != '\0'; ++k) { l[k - j - 1] = algorithm[k]; } //计算两个被提取出来的字符串长度 for (i = 0; f[i] != '\0'; ++i) { lenf += 1; } for (i = 0; l[i] != '\0'; ++i) { lenl += 1; } //把字符串转换为数字 for (i = 0; i 赞(0) 打赏