Updated March 4, 2023
Difference between sprintf vs snprintf
sprintf and snprintf are the functions used in C language to write the programs were both works in a different manner. String print represented by sprintf stores the output on character buffer noted in sprintf and not in the console as other functions. A formatted string is stored in the variable for sprintf. The output of printf is redirected to any buffer so that repetition of the string is avoided in snprintf. The buffer can be mostly an array buffer and ‘n’ represents the number of characters to be written in the buffer. Null character can also be written in snprintf.
Head to Head Comparison Between sprintf vs snprintf (Infographics)
Below are the top 7 differences between sprintf vs snprintf:
Comparison Table of sprintf vs snprintf
Let’s find the comparison in table format below.
| sprintf | snprintf |
| The expression takes the destination in the form of a string along with different arguments where more space is taken as it does not consider the bytes it possesses to write the code. | The expression snprintf takes the destination with a fixed or clear idea of strings so that changes in the string do not affect the performance or storage of the function. |
| We can find sprintf in the standard library. There is no limitation to the characters written to the buffer as it is part of the standard library. | We cannot find snprintf in the standard library. There is a limit to the number of characters to be entered in the buffer. |
| Buffer size need not be mentioned while using sprintf. Also, it doesn’t produce the number of output characters. Null terminator is not present in sprintf and it should be managed by the user itself if needed. | While using snprintf, it is necessary to mention the size of the buffer to be used in the function. This helps the function to eliminate any null characters if present in the function and to manage the null terminator by itself. |
| The behavior of sprintf is not changed from one system to other and hence it can be implemented in a similar manner in the systems. Sprintf can be implemented by calling snprintf in the programs. | Snprintf cannot be implemented in a similar manner in all systems. It changes its behavior from one system to other. Also, we cannot implement snprintf with sprintf. |
| The values are returned by reading the characters till 255 of the string and if the characters are more than that, sprintf will avoid those characters. Null is also considered in this operation. | The values are always returned by reading the entire string even if the characters are more than 255. Here null character is terminated and not taken into consideration at all. |
| Security is less in sprintf as it does not protect the string if it is more than 255 characters. And if a null character is present, there is a chance of modification of string. | Snprintf is more secure and if the string number overruns the characters, the string is protected in the buffer even if the format is different. |
| It works with n characters and nth location and hence the location of null character is not considered at all. Allocation of null character memory is preserved in sprintf. | All the characters beyond n-1 is omitted where n is the location of null character. Hence the resulting string is always less than 1 character. |
Key Differences of sprintf vs snprintf
Sprintf stores and converts the values if needed with the help of format parameter and the value is stored in bytes. This helps to identify the address easily in the function. A null character is placed in the end and hence it is necessary to make sure that enough space is allocated to accommodate the null character as well. Conversion types are also provided in the function to make it easy for users. The main difference between sprintf and snprintf is that in snprintf, the buffer number to be specified in the function which is represented by ‘n’ in snprintf.
While doing concatenation, the functions are used differently in both sprintf and snprintf. For example, if we need to print ‘My name is Nelson’ in both sprintf and snprintf the method is different.
Sprintf example:
Sprintf (buf, “%s.%s”, buf, “My name “);
Sprintf (buf, “%s.%s”, buf, “is Nelson”);
Snprintf example:
Snprintf (buf, sizeof(buf), “%s”, “My name “);
Snprintf (buf+strlen(buf), sizeof(buf)-strlen(buf), “%s”, ” is Nelson”);
The resulting string is stored in buffer and hence it is necessary for snprintf to give the number of buffers in the code itself.
In snprintf, a null character is automatically added to the character format and this is included in the size check. Hence, when the size of characters is checked for snprintf, null character is also added to the format. Null character is not automatically added to sprintf format and not included in size check as well. When the size is checked in sprintf, null character is omitted and the developer should be cautious while using sprintf and snprintf alternately. So, it is safe to enter the size in the function and to make the note of the same while the program runs.
The size of buffer string is not returned after the program run in sprintf. This makes the developer to check the size manually and make a note of the same. In snprintf, the size of the string is returned and if the size of the string is the same as the size of the buffer, then the smaller size is returned. It is important to make a note of the difference and if needed, to add a conservative buffer in the program. This conservative buffer has small memory for buffer and this memory allocates the string if the string is larger than the buffer. If a larger buffer is needed, it creates by itself, or else the program is stopped saying that it is exciting from the program.
In C language, sprintf and snprintf can be used alternatively if buffer conditions or string length does not matter to the user much. Snprintf is safer to use because characters are not omitted and it is stored in the buffer for later usage. Both sprintf and snprintf store the string and produces the output as needed by user.
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