Add graph references

references/igraph-1.0.1/examples/simple/safelocale.c

@@ -0,0 +1,52 @@
+
+#include <igraph.h>
+
+#include <locale.h>
+#include <stdio.h>
+#include <string.h>
+
+int main(void) {
+    const char *filename = "weighted.gml";
+    igraph_t graph;
+    igraph_safelocale_t loc;
+
+    /* Initialize the library. */
+    igraph_setup();
+
+    /* Attempt to set a locale that uses a decimal comma. Locale names
+     * differ between platforms, and not all locales are available,
+     * so the locale change may not be successful. */
+    const char *locname = setlocale(LC_ALL, "de_DE");
+    struct lconv *lc = localeconv();
+    if (strcmp(lc->decimal_point, ",")) {
+        /* If decimal point is not a comma, presumably because the requested
+         * locale was not available, report locale information. */
+        fprintf(stderr, "setlocale() returned '%s', decimal point is '%s'\n",
+                locname ? locname : "NULL",
+                lc->decimal_point);
+    }
+
+    FILE *file = fopen(filename, "r");
+    if (! file) {
+        fprintf(stderr, "Cannot open %s file.\n", filename);
+        exit(1);
+    }
+
+    /* An attribute table is needed to read graph attributes. */
+    igraph_set_attribute_table(&igraph_cattribute_table);
+
+    /* At this point, the current locale may use decimal commas.
+     * We temporarily set a C locale using enter_safelocale() to
+     * allow the GML reader and writer to work correctly.*/
+    igraph_enter_safelocale(&loc);
+    if (igraph_read_graph_gml(&graph, file) != IGRAPH_SUCCESS) {
+        fprintf(stderr, "Reading %s failed.\n", filename);
+        abort();
+    }
+    igraph_write_graph_gml(&graph, stdout, IGRAPH_WRITE_GML_DEFAULT_SW, NULL, "");
+    igraph_exit_safelocale(&loc);
+
+    igraph_destroy(&graph);
+
+    return 0;
+}