7.3: String Formatting
- Page ID
- 10702
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String formatting uses a process of string interpolation (variable substitution) to evaluate a string literal containing one or more placeholders, yielding a result in which the placeholders are replaced with their corresponding values.[1]
Discussion
Most current programming languages provide one or more string formatting functions that use a template string with placeholders and optional alignment, width, and precision indicators to generate formatted output.
Language | Function | Examples |
---|---|---|
C++ | snprintf() | snprintf(str, sizeof(str), "Hello %s!", name); |
C# | Format() | String.Format("Hello {0}!", name); |
Java | format() | String.format("Hello %s!", name); |
JavaScript | template literal | `Hello ${name}`; |
Python | format() | "Hello {}!".format(name) |
Swift | interpolationString() | "Hello \(name)!" String(format:"%.2f", value) |
String interpolation, like string concatenation, may lead to security problems. If user input data is improperly escaped or filtered, the system may be exposed to code injection.[2]
Key Terms
- code injection
- The exploitation of a computer bug that is caused by processing invalid data.[3]
- formatting
- Modifying the way the output is displayed.
- string interpolation
- Evaluating a string literal containing one or more placeholders, yielding a result in which the placeholders are replaced with their corresponding values.