The sprintf() function in PHP is used to format strings and return results. 1. Formats such as %.2f and %.1f can be automatically rounded by formatting characters such as %.2f and %.1f; 2. Complement and width control can be implemented through d or M, indicating complementary or fill spaces respectively; 3. String truncation and splicing use %.10s or .10s to limit length and alignment; 4. When using multiple parameters in a mixed manner, %s, %d, and %f correspond to strings, integers, and floating-point numbers, respectively, and the order must be consistent. This function is very practical in generating logs, reports and other scenarios, making the code more neat and controllable.

In PHP, sprintf() is a very practical function to format strings. It will not output the result directly, but will return the formatted string, which will facilitate us to assign values ??to variables or perform further processing.

Below are some common sprintf() format usage examples, suitable for beginners to understand and advanced use.

Formatted numbers to fixed decimal places

If you need to keep floating point numbers two decimal places, you can use a format like %.2f :

 $price = 19.9;
$formatted = sprintf("Price is %.2f yuan", $price);
// Output: The price is 19.90 yuan

This usage is very common when displaying amounts and statistics. Note that it will automatically round up here.

• If you want to keep a decimal, use %.1f
• Don't want to keep the decimals? %d can be used to force convert to integers (but be careful of data loss)

Zero Compensation and Width Control

Sometimes we need to generate fixed-length strings, such as order number, log timestamp, etc. At this time, you can use the format d to make up for zeros:

 $number = 7;
$formatted = sprintf("number: d", $number);
// Output: No.: 0007

This writing method is also very suitable for months, dates and other scenarios.

• d can ensure that the single digit number is first added to 0, such as 05 instead of 5
• If you want to leave spaces instead of making up zeros, you can use M so that the left side will be filled with spaces

String truncation and stitching

sprintf() is also suitable for string operations, such as limiting the maximum length:

 $name = "Hello World";
$formatted = sprintf("name: .10s", $name);
// Output: Name: Hello W

In the above example .10 means that the first 10 characters are taken up at most. .10s means that the width of 10 characters is occupied in total. If it is insufficient, the spaces will be filled with left alignment.

• If you only want to truncate without considering the width, you can write %.10s directly
• Note that Chinese characters may not be applicable in this way, because one Chinese character counts multiple bytes

Multi-parameter mix

In actual development, we often have to combine multiple types of data. For example:

 $name = "Alice";
$age = 28;
$height = 165.5;

echo sprintf("name: %s, age: %d years old, height%.1f cm", $name, $age, $height);
// Output: Name: Alice, Age: 28 years old, height 165.5 cm

This example shows how to process strings, integers, and floating-point numbers in a statement.

• %s corresponds to string
• %d corresponds to integer
• %f corresponds to floating point number
• The parameter order must correspond to the format character one by one.

Basically these common uses. Although it seems simple, it is very useful in format alignment and output control, especially when generating logs, reports, and exporting files. Mastering sprintf() will make your code more neat and controllable.

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