Using argc and argv in C Programming
Discover how to utilize the argc and argv parameters in C programming to handle command-line arguments efficiently. Learn how to convert command-line input into integers, error handling, and more with illustrative code examples and explanations by Yung-Hsiang Lu from Purdue University.
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Presentation Transcript
How to Use argc and argv Yung-Hsiang Lu Purdue University 1
#include <stdio.h> #include <stdlib.h> int main(int argc, char * * argv) { if (argc < 2) { printf("Need a number\n"); return EXIT_FAILURE; } int val = strtol(argv[1], NULL, 10); val += 10; printf("argv[1] = %s\n", argv[1]); printf("val = %d\n", val); return EXIT_SUCCESS; } 2
#include <stdio.h> #include <stdlib.h> int main(int argc, char * * argv) { if (argc < 2) { printf("Need a number\n"); return EXIT_FAILURE; } int val = strtol(argv[1], NULL, 10); val += 10; printf("argv[1] = %s\n", argv[1]); printf("val = %d\n", val); return EXIT_SUCCESS; } check the value use argv[1] 3
#include <stdio.h> #include <stdlib.h> int main(int argc, char * * argv) { if (argc < 2) { printf("Need a number\n"); return EXIT_FAILURE; } int val = strtol(argv[1], NULL, 10); val += 10; printf("argv[1] = %s\n", argv[1]); printf("val = %d\n", val); return EXIT_SUCCESS; } an error message 4
#include <stdio.h> #include <stdlib.h> int main(int argc, char * * argv) { if (argc < 2) { printf("Need a number\n"); return EXIT_FAILURE; } int val = strtol(argv[1], NULL, 10); val += 10; printf("argv[1] = %s\n", argv[1]); printf("val = %d\n", val); return EXIT_SUCCESS; } the program stops with an error 5
#include <stdio.h> #include <stdlib.h> int main(int argc, char * * argv) { if (argc < 2) { printf("Need a number\n"); return EXIT_FAILURE; } int val = strtol(argv[1], NULL, 10); val += 10; printf("argv[1] = %s\n", argv[1]); printf("val = %d\n", val); return EXIT_SUCCESS; } convert argv[1] to an integer store the integer in val 6
#include <stdio.h> #include <stdlib.h> int main(int argc, char * * argv) { if (argc < 2) { printf("Need a number\n"); return EXIT_FAILURE; } int val = strtol(argv[1], NULL, 10); val += 10; printf("argv[1] = %s\n", argv[1]); printf("val = %d\n", val); return EXIT_SUCCESS; } add 10 to val 7
#include <stdio.h> #include <stdlib.h> int main(int argc, char * * argv) { if (argc < 2) { printf("Need a number\n"); return EXIT_FAILURE; } int val = strtol(argv[1], NULL, 10); val += 10; printf("argv[1] = %s\n", argv[1]); printf("val = %d\n", val); return EXIT_SUCCESS; } print the string argv[1] and the integer val 8
#include <stdio.h> #include <stdlib.h> int main(int argc, char * * argv) { if (argc < 2) { printf("Need a number\n"); return EXIT_FAILURE; } int val = strtol(argv[1], NULL, 10); val += 10; printf("argv[1] = %s\n", argv[1]); printf("val = %d\n", val); return EXIT_SUCCESS; } the program successfully prints the value 9
#include <stdio.h> #include <stdlib.h> int main(int argc, char * * argv) { if (argc < 2) { printf("Need a number\n"); return EXIT_FAILURE; } int val = strtol(argv[1], NULL, 10); val += 10; printf("argv[1] = %s\n", argv[1]); printf("val = %d\n", val); return EXIT_SUCCESS; } 10
