Which command would you use to convert a numeric string "123" to an integer?

The command that correctly converts a numeric string like "123" to an integer in C++ is stoi("123"). This function stands for "string to integer" and is part of the C++ standard library. It takes a string argument that represents a numeric value and returns its integer equivalent.

The stoi function also includes error handling capabilities, so if the string cannot be converted to an integer due to invalid characters, it will throw an exception, allowing the programmer to manage the error appropriately.

In contrast, other choices do not represent valid C++ functions for this operation. For instance, parseInt("123") is typically associated with languages like JavaScript and is not found in C++. Similarly, convert("123") does not correspond to any standard C++ function for converting a string to an integer, making it invalid in this context. Lastly, using int("123") is incorrect because the int keyword in C++ does not function in this manner; it cannot be used to cast a string directly to an integer, as it requires a numeral type or variable that is already convertible.

Thus, stoi("123") is the appropriate choice for converting a numeric string to an integer