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Correct escape sequence in printf statement #98

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Correct escape sequence in printf statement #98

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7c1a3cf
Correct escape sequence in printf statement
kkaname Dec 15, 2025
a01ba79
Fix printf argument to avoid warning
kkaname Dec 15, 2025
e4b721e
Implemented code for 32 bit for more flexibility
kkaname Dec 15, 2025
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2 changes: 1 addition & 1 deletion chapter_1/exercise_1_02/printf_argument.c
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
#include <stdio.h>

int main(void) {
printf("hello, world\\c");
printf("hello, world\c"); /*prints warning: unknown escape sequence '\c' */
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⚠️ Potential issue | 🟡 Minor

🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
# First, explore the repository structure
find . -name ".clang-format" -o -name ".clang-format-ignore" -o -name "clang-format.cfg" | head -20

Repository: ohkimur/the-c-programming-language-2nd-edition-solutions

Length of output: 115

🏁 Script executed:

#!/bin/bash
# Check if the file exists and read its content
if [ -f "chapter_1/exercise_1_02/printf_argument.c" ]; then
  echo "=== File found ==="
  cat -n "chapter_1/exercise_1_02/printf_argument.c"
else
  echo "File not found. Searching for similar file names..."
  find . -name "*printf*" -type f 2>/dev/null | head -20
fi

Repository: ohkimur/the-c-programming-language-2nd-edition-solutions

Length of output: 297

🏁 Script executed:

#!/bin/bash
# Check for any clang-format configuration files in the repo
git ls-files | grep -E "(clang-format|\.clang|format\.yaml|format\.json)" || echo "No clang-format files found via git ls-files"

Repository: ohkimur/the-c-programming-language-2nd-edition-solutions

Length of output: 125

🏁 Script executed:

#!/bin/bash
# Read the clang-format configuration
cat .clang-format

Repository: ohkimur/the-c-programming-language-2nd-edition-solutions

Length of output: 133

🏁 Script executed:

#!/bin/bash
# Apply clang-format and see what changes it would make
if command -v clang-format &> /dev/null; then
  echo "=== clang-format would change to: ==="
  clang-format -style=file chapter_1/exercise_1_02/printf_argument.c
else
  echo "clang-format not available, but based on LLVM style:"
  echo "Inline comments should have 1 space, not 5 spaces"
fi

Repository: ohkimur/the-c-programming-language-2nd-edition-solutions

Length of output: 202

🏁 Script executed:

#!/bin/bash
# Verify the \c escape sequence behavior in C
# Check C standard behavior and common compiler outputs
cat <<'EOF'
Escape sequence verification:
- \c is NOT a standard C escape sequence
- Standard C defines: \n, \t, \r, \a, \b, \f, \v, \\, \', \", \?, \0-7 (octal), \x (hex)
- \c is implementation-defined and typically generates a compiler warning
- The exact warning text varies by compiler (GCC vs Clang vs MSVC)

Current code says: "/*prints warning: unknown escape sequence '\c' */"
Issues:
1. "prints warning" is misleading - the compiler emits the warning, not the program
2. Hard-coded GCC diagnostic text is not portable across compilers
3. Spacing before comment violates LLVM clang-format style (5 spaces instead of 1)
EOF

Repository: ohkimur/the-c-programming-language-2nd-edition-solutions

Length of output: 714

Fix inline comment clarity and clang-format spacing

The code correctly introduces an invalid escape sequence, but the inline comment has two issues:

  • The comment states "prints warning" which is misleading—the compiler emits the warning at compile time, not at runtime.
  • The hard-coded GCC diagnostic text is not portable across different compilers.
  • Spacing before the comment violates the repository's LLVM clang-format style (currently 5 spaces; should be 1 space).

Adjust the comment to be compiler-agnostic and fix the spacing:

-    printf("hello, world\c");     /*prints warning: unknown escape sequence '\c' */
+    printf("hello, world\c");  /* compiler warning: invalid escape sequence '\c' */

Then run clang-format to ensure it matches the repository's style configuration.

📝 Committable suggestion

‼️ IMPORTANT
Carefully review the code before committing. Ensure that it accurately replaces the highlighted code, contains no missing lines, and has no issues with indentation. Thoroughly test & benchmark the code to ensure it meets the requirements.

Suggested change
printf("hello, world\c"); /*prints warning: unknown escape sequence '\c' */
printf("hello, world\c"); /* compiler warning: invalid escape sequence '\c' */
🧰 Tools
🪛 GitHub Actions: C CI

[error] 4-4: clang-format violation detected: code should be clang-formatted [-Wclang-format-violations].

🤖 Prompt for AI Agents 
In chapter_1/exercise_1_02/printf_argument.c around line 4, the inline comment
after the printf call is misleading and misformatted: change the comment to be
compiler-agnostic (e.g., note that the string contains an invalid/unknown escape
sequence and that a compiler may emit a warning) and reduce the spacing before
the comment to a single space to conform to LLVM/clang-format style; after
editing, run clang-format on the file to ensure spacing and style match the
repository configuration.

return 0;
}
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