From 442a49ad5a48d417345959b903ae6a6d32d55759 Mon Sep 17 00:00:00 2001 From: Haidong Ji Date: Fri, 15 Apr 2022 15:51:30 -0500 Subject: Great C programming fun Excellent fundamentals and displine training, many tools and techniques exercises: gdb, emacs, valgrind, git --- 19_bits_arr/.gitignore | 1 + 19_bits_arr/Makefile | 2 ++ 19_bits_arr/README | 47 ++++++++++++++++++++++++++++++++ 19_bits_arr/bits_ans.txt | 10 +++++++ 19_bits_arr/grade.txt | 19 +++++++++++++ 19_bits_arr/numToBits.c | 70 ++++++++++++++++++++++++++++++++++++++++++++++++ 6 files changed, 149 insertions(+) create mode 100644 19_bits_arr/.gitignore create mode 100644 19_bits_arr/Makefile create mode 100644 19_bits_arr/README create mode 100644 19_bits_arr/bits_ans.txt create mode 100644 19_bits_arr/grade.txt create mode 100644 19_bits_arr/numToBits.c (limited to '19_bits_arr') diff --git a/19_bits_arr/.gitignore b/19_bits_arr/.gitignore new file mode 100644 index 0000000..1be726c --- /dev/null +++ b/19_bits_arr/.gitignore @@ -0,0 +1 @@ +numToBits diff --git a/19_bits_arr/Makefile b/19_bits_arr/Makefile new file mode 100644 index 0000000..b0fe89a --- /dev/null +++ b/19_bits_arr/Makefile @@ -0,0 +1,2 @@ +numToBits: numToBits.c + gcc -o numToBits -pedantic -std=gnu99 -Wall -Werror numToBits.c diff --git a/19_bits_arr/README b/19_bits_arr/README new file mode 100644 index 0000000..019d6cf --- /dev/null +++ b/19_bits_arr/README @@ -0,0 +1,47 @@ +For this problem, you will be splitting numbers (a 32 bit integer) +up into their individual bits. I have provided a function for you +(getNthBit) which will return a specific bit from a number. For example, +getNthBit(x,0) would return the first (0th) bit, getNthBit(x,1) would +return the next bit, and so on. + +While we normally use "int" for our numbers, we are using "uint32_t". +This is just like "int" except that they are unsigned ints which are +guaranteed to be 32 bits long (by contrast, the normal "int" type +is signed, and there are no guarantees as to how many bits are in it). +We are doing this to be precise and correct: you can use a uint32_t +in much the same way as an int. + +1. Open the file numToBits.c + Find the function + +void numToBits(uint32_t * nums, int nNums, int * bits, int nBits) ; + + This function takes in two arrays: nums (of length nNums), and + bits (of length nBits). This function should: + - Check that there is enough space in bits to hold all the bits + of "nums". Note that each number in "nums" will results in 32 + bits in "bits". If this is not true, your function should + print a message with the format: + "Invalid call to numToBits! nBits is %d, nNums is %d\n", + (where the first %d is nBits, and the second %d is nNums) + then return without doing anything else. + + - Put the individual bits of each number into the "bits" array. + The bits put into this array should be ordered so that the first + 32 bits represent nums[0], the next 32 bits are nums[1], and so + on. Within each number, the most significant bit (bit 31) should + come first, and the least significant bit (bit 0) should come last. + That is, bits[0] should be bit 31 of nums[0], bits[1] should + be bit 30 of nums[0], and so on. + + + + 2. Compile and test your code. + We have provided a main function which will print test cases + and your function's answer for them. We have provided the + correct output in bits_ans.txt + + 3. Submit as usual + + + diff --git a/19_bits_arr/bits_ans.txt b/19_bits_arr/bits_ans.txt new file mode 100644 index 0000000..9702a22 --- /dev/null +++ b/19_bits_arr/bits_ans.txt @@ -0,0 +1,10 @@ + 1 ( 1) => 00000000000000000000000000000001 + 2 ( 2) => 00000000000000000000000000000010 + 3 ( 3) => 00000000000000000000000000000011 + 4 ( 4) => 00000000000000000000000000000100 + 5 ( 5) => 00000000000000000000000000000101 + 15 ( F) => 00000000000000000000000000001111 + 109 ( 6D) => 00000000000000000000000001101101 + 123456789 ( 75BCD15) => 00000111010110111100110100010101 + 987654321 (3ADE68B1) => 00111010110111100110100010110001 +Invalid call to numToBits! nBits is 223, nNums is 7 diff --git a/19_bits_arr/grade.txt b/19_bits_arr/grade.txt new file mode 100644 index 0000000..54495d6 --- /dev/null +++ b/19_bits_arr/grade.txt @@ -0,0 +1,19 @@ +Grading at Wed 20 Oct 2021 02:04:01 AM UTC +Attempting to compile numToBits.c +Your file matched the expected output +Your output matched what we expected +Removing your main() and replacing it with our own to run more tests... +################################################# +testcase2: +array size:0 was Correct +################################################# +testcase3: +array size:1 was Correct +################################################# +testcase4: +array size:100 was Correct +################################################# +testcase5: +array size:5000 was Correct + +Overall Grade: A diff --git a/19_bits_arr/numToBits.c b/19_bits_arr/numToBits.c new file mode 100644 index 0000000..c7538da --- /dev/null +++ b/19_bits_arr/numToBits.c @@ -0,0 +1,70 @@ +#include +#include +#include + +/* + * Helper function that retrieves numbers 'bit' value + * ie: 1's 31st bit is 1 + */ +int getNthBit(uint32_t number, int bit) { + if (bit <0 || bit >= 32) { + printf("Bit %d is invalid\n", bit); + exit (EXIT_FAILURE); + } + return (number & (1< ", nums[i], nums[i]); + for (int j = 0; j < 32; j++) { + printf("%d", bits[i*32 + j]); + } + printf("\n"); + } +} + +int main(void) { + uint32_t array1[] = { 1, 2, 3, 4, 5, 15, 109}; + uint32_t array2[] = { 123456789, 987654321 }; + int bits[7*32-1]; + doTest (array1, 7); + doTest (array2, 2); + numToBits(array1,7, bits , 7*32-1); + return EXIT_SUCCESS; +} -- cgit v1.2.3